Synapsida

All the World's Antelopes: Duikers of Bush and Forest

2026-10-18T16:38:23.557+01:00

Common duiker

While the term "antelope" probably conjures up the image of something like a gazelle or a blackbuck, a great many species are much smaller than these animals. Often collectively referred to as "dwarf antelopes", they are scattered across the wider antelope family tree, belonging to several different groups. Being small and relatively inconspicuous helps when you're a herbivore, even if it isn't the only route to survival.

In terms of number of species, the duikers, technically referred to as the subfamily Cephalophinae, are one of the more successful groups of such small antelopes. The exact number of duiker species has fluctuated widely over the years, with some estimates reaching as high as 25. The latest version of the Mammal Diversity Database, however, lists 21, so that is what I am going with.

The best-known species is the bush duiker (Sylvicapra grimmia), also known as the "common duiker". It is the most widespread of all antelopes, being found through essentially the whole of sub-Saharan Africa outside of the rainforests. It was also the first species to be described, back in 1758, when (like all antelopes at the time) it was listed as a type of goat.

Perhaps ironically given its "common" moniker, it is also arguably the least typical of all the duiker species. Like other duikers, it is a small antelope, standing between 39 and 68 cm (15 to 27 inches) tall at the shoulder. This is taller than many other duiker species, due to it having proportionately longer legs, although the body is otherwise similar in form. The colour varies from grey to yellowish-fawn across different parts of its wide range, and males have straight, vertical horns, typically around 10 cm (4 inches) in length.

The reason for these longer legs is that, as its name suggests, the bush duiker lives in moderately open country. Living across so much of Africa, the details of this vary considerably, including bush, veldt, and savannah, but they avoid dense forests just as much as they do inhospitable deserts. They have even been found close to the snowline at 4,300 metres (14,000 feet) elevation on Mount Kenya. Having said that, they do require longer vegetation to escape into, and so will avoid barren areas or those covered only with short grass.

Tall grass and scattered ferns are ideal, but, while they are unlikely to forage in wooded areas, any shrubby vegetation will suffice. Although they can jump up to 1.8 metres (6 feet) if they have to, when threatened, they are more likely to dart for cover, ducking below any suitable obstacles that might impede a predator. This is where the name comes from, since it is the Dutch/Afrikaans word for "diver". (In English, if you're wondering, it rhymes with 'biker', although it doesn't in the original language.)

They are browsing animals, feeding on a wide variety of low vegetation, mostly leaves and stems, although they will pull up some plants to get at the roots. In the drier parts of their range, on the edge of the Kalahari, they eat melons for their water; otherwise, while they can get by for several days without drinking, they will take water whenever they get the opportunity. Unusually for an antelope, they have also been recorded intentionally eating animal matter (as opposed to the odd insect that happens to be sitting on a leaf), and even hunting some small ground-dwelling birds.

Like most small antelopes, they are solitary, meeting up for just a few days each year when the females come into heat. Both sexes have scent glands in front of their eyes with prominent slit-shaped openings, and the exact scent produced varies between males and females. Males leave their scent on branches, rocks, and other landmarks, marking out territories of around 0.25 km² (60 acres) each, which they defend through combat with their rivals. Having said which, if they aren't competing for mating opportunities, bush duikers are quite friendly with one another, grooming each other if they happen to meet up and hanging around together for several hours before parting again.

There is no particular breeding season, although births are most common around the start of the rainy season - the timing of which varies depending on where in Africa they happen to be. Otherwise, their reproduction is similar to that of other antelopes. Courtship consists of the male chasing the female until she relents and slows down, advertising her receptivity with urine scent marks. They give birth to a single young about 200 days later, hiding it in cover and browsing nearby, only returning to allow it to suckle.

Blue duiker

The blue duiker (Philantomba monticola) is the smallest of all duiker species, standing just 30 to 38 cm (12 to 15 inches) tall at the shoulder. The colour is somewhat variable, although describing it as "blue" is perhaps something of a stretch. It is most typically a brownish grey, but this varies between subspecies, with some having reddish flanks, which may be vaguely or clearly demarcated from the more typically coloured rump. Both sexes have horns, but they are only 3 to 5 cm (1 to 2 inches) long in the males, and even shorter in the females.

It is found across central Africa, from Nigeria to Angola on the Atlantic coast and from Kenya to Mozambique on the eastern side of the continent. Two subspecies live in an entirely separate area along the east coast of South Africa, and have sometimes been considered to represent a distinct species, although this is not followed by most modern sources.

As with all duikers other than the bush species, they are forest dwellers. They inhabit a wide range of different forest types, from the dense jungles of the Congo to the more scattered low-reaching woodlands of black witch-hazel in South Africa. They tend to prefer forests with a good mix of tree types, and are most commonly found foraging in clearings where there is comparatively little undergrowth, but nearby cover is still easy to reach.

Blue duikers prefer to feed on freshly fallen fruit and leaves, although, especially in South Africa, where the forests are less dense, they will also feed directly from trees and bushes. The specific fruit that they eat varies with locality, but studies have identified those from umbrella trees, manguella, and African nutmeg as favourites in some parts of their range.

Like other duikers, they are diurnal, but are most active shortly after dawn and just before sunset. They are usually described as solitary, although reports of apparently mated pairs are more common than that might suggest - the fact that they are small animals prone to hiding in undergrowth may also mean that such pairs are underreported. Indeed, pairs are most often recorded from nighttime surveys, where they can be spotted sleeping next to one another, rather than when they are foraging during the daytime.

Population estimates are similarly unreliable, varying depending on what method is used, but they seem to be quite numerous in most places they are found. They typically range over areas as small as three hectares (7½ acres), although males may make short-range forays beyond. Both sexes are territorial, although males scent-mark more often than females, perhaps indicating a more defensive attitude. Even young leaving home to set up their own territories only travel about 1.5 km (just under a mile) before settling down but even so, humans disrupting their forests can have a negative effect.

When alarmed, they are most likely to freeze in the first instance. They let out a shrill alarm call if they feel the need to flee, sometimes adding to this by thumping the ground with their hooves as they set off. When this does happen, however, they don't run for long, taking refuge in nearby undergrowth at the earliest opportunity.

Maxwell's duiker

Maxwell's duiker (Philantomba maxwellii) is very similar to its close relative. It is slightly larger, but is perhaps most readily distinguished by the presence of two reddish stripes on the head, although these become fainter with age. It lives in the forests of West Africa, from Senegal to Ghana, living in much the same habitat as the blue duiker. Its diet is similar too, with estimates suggesting that at least three-quarters of it consists of fruits and legumes, most often freshly fallen from trees rather than plucked. Often, they are observed hanging around underneath groups of monkeys foraging in the trees, picking up whatever gets dropped. The remainder of the diet consists of a mix of leaves, fungi, and flowers.

The evidence for living in mated pairs is stronger with Maxwell's species as well. While each member of a pair has its own separate territory, these overlap by about 80% with each other and by less than 1% with those of their other neighbours. These are around the same size as those of blue duikers, with the animals showing a similar aversion to travel. Males mark the boundary of their territories with dung and other scent marks, and are highly aggressive in defending them.

With most antelopes, the defender will engage in some form of ritualised posturing to deter intruders before any energy is wasted on fighting. But Maxwell's duiker doesn't seem to have time for that; they charge straight in to headbutt each other with such force that one combatant is often flipped into the air. The following fight is intense but brief, with at most two minutes before the loser makes a run for it, angrily pursued by the victor until he is well out of range.

In 2010, a review of the animals at the eastern end of Maxwell's duiker's range identified them as a new species. This decision was made on the basis of clear differences in the skull shape (most notably, a narrower nose) but was also supported by genetic evidence that has since been confirmed. As a result, we recognise Walter's duiker (Philantomba walteri) as distinct from Maxwell's, despite its similar appearance. It is slightly smaller, but otherwise hard to distinguish without detailed skull measurements or genetic data.

It lives in Togo, Benin, and western Nigeria, although the full extent of its range is unclear, as so few individuals have been definitively identified - a 2016 review was only able to find mention of 41. For the same reason, and because it has only been so recently identified as a species, we know little about it as distinct from its more westerly relative, although one 2022 study may indicate a greater willingness to eat leaves rather than fruit. This may be because the area it lives in is a wide stretch of savannah and scrubland between denser forests, so suitable fruit trees may simply be less available.

The other three species I have mentioned are all common and at least reasonably widespread. With so few individuals located, we don't really know about the conservation status of Walter's species, although the fact that most of them were found in bushmeat markets is hardly promising.

There are, however, as many as 17 other species of duiker, and next time, I will be taking a look at some of them.

[Photos by "Chuckupd", Derek Keats, and Charles J. Sharp, from Wikimedia Commons. Cladogram adapted from Ghassemi-Khademi and Hamidi, 2019.]

The Family Lives of Elephants

2026-10-11T16:45:06.805+01:00

In 1961, Irven Buss published a scientific paper in which he proposed that the fundamental social unit among African elephants could best be described as a family group. While this put the subject on a firm scientific footing for the first time, he was hardly the first person to have noticed. Even white Europeans had at least mentioned the idea going back to the 19th century, particularly with regard to the Asian elephants living in the British Raj.

Not to mention that the locals had surely noticed, and just not written scientific papers about it.

Nonetheless, Buss, like the big game hunters before him, assumed that these families were led by the largest and strongest males. That must have seemed natural enough, and would fit with the behaviour many other mammals, but even in the 1960s, studies on elephant culls in Uganda began to reveal that the real leaders were the oldest and most experienced females. Maternity testing since then has confirmed the extent to which the families are, like those of humans, composed of very closely related individuals, and that these are organised in at least two levels of higher social grouping, each less related than the one below it.

The oldest female in the group, the matriarch, is of pivotal importance to the family she leads. Studies have shown that the older the matriarch, the more infants the group is able to raise, and the more other families will want to associate with them. The loss of a matriarch can temporarily weaken a family, and, in severe cases, lead to a localised social collapse with potentially dire consequences for all involved.

This combination of regular family life and a matriarchy is relatively rare among mammals. There are, of course, many pack and herd animals that associate together in large groups, and the females may often be the ones that lead them towards new food sources when they move. But true matriarchies, where the oldest female forms the linchpin of the closely related social group, are found only among elephants, cetaceans, and two species of primates: bonobos and (some) humans.

There are three living species of elephants: the Asian elephant, the African bush elephant, and the African forest elephant; the latter not being identified as a distinct species until 2000. So far as we can tell, all three display similar social organisation, and, for what it's worth, this implies that much the same was probably true of their closest extinct relatives, such as the woolly mammoth.

The bush elephants (Loxodonta africana) of the Amboseli National Park, in southern Kenya have been studied since the early 1970s, providing us with the basis for an unusually long-term population study. While bush elephants (like the other two species) are formally listed as an endangered species globally, they have been doing relatively well in this particular area. When the study started in 1972, researchers estimated the total population as around 600, but in 2025, we knew of 2,000 elephants in the area. This is due to a combination of high tourist activity, active game wardens (fewer elephants means less tourist dollars), and, to some extent, protection by the local Maasai people.

Crucially, every elephant that has lived nearby during that time has been catalogued as part of the ongoing research project. We obviously don't have genetic data on all of them, but what we do have confirms that the maternity records based on simple observation are accurate. Paternity, as one might expect, has proved much harder to establish. But, bearing that obvious limitation in mind, a study published earlier this year gathered together many of these old records, supported by genetic data, to give a detailed insight into the family lives of elephants in Amboseli over the last 50 years.

In total, 84 families of elephants have been identified over the years at Amboseli, 67 of which are still around. Some are small, with as few as five members, but many are much larger, reaching up to 60 individuals. They are, from a human perspective, extended families, rather than a direct lineage of grandmother to mother to daughter. In fact, the average relatedness between any two members of a given family is that of aunt to niece, suggesting that each is most likely to be started by a core group of sisters.

Obviously, given the time involved, none of the matriarchs at the beginning of the study are still with us. Indeed, each family had, on average, four matriarchs over the 50-year period. Typically, female elephants become matriarchs at around 39 years of age, and very few manage it before of 20 - those that do are typically orphans, with no related older females around to fall back on. The length of time for which they hold the position is hard to evaluate directly, because we have to exclude all of those who were either already in place in 1972, or still were as of 2025. But the best guess from the study is an average of about 19 years, which is not insignificant, even for an elephant.

On fifteen occasions, new families arose when an existing one split into two. This is, perhaps, an inevitable consequence of the steadily increasing population of elephants locally over the decades, with some of the groups becoming too unwieldy to continue. However, they were also more common when times were harsh, such as during a drought. At these times, perhaps, splitting up into smaller groups that could forage separately without exhausting the same stock of food made sense.

One might expect that such splits would tend to be fairly even, but more often than not, the new group was much smaller than the one continuing under the existing matriarch. In a typical split, for example, only a third of the female elephants would lead with their new matriarch. Such splits occurred along family lines themselves, with those most distantly related to the old matriarch likely to leave to follow a closer relative. This would suggest a deep level of bonding among the animals, with them aware, on some level, of which members of their family they share a deeper kinship with, perhaps reinforced by their behaviour towards one another down the years.

But that's not a universal rule. On occasion, a female from one family left to join up with another one. This sort of event, while rare, is still not entirely random, since the departing elephant will at least pick a new family she has some relationship with, but it does illustrate that something - social compatibility, we might say - can override family loyalty.

The authors point out that it doesn't follow that the departing members didn't keep in touch with one another. We know that elephants can communicate over long distances, using a mix of scent marking, and calls that can even be transmitted subsonically through the ground.

There are also instances where an entirely new family group, not especially related to one another, forms when two or more orphans gather together for companionship, with one (in one case, as little as eight years old) becoming a matriarch by default. This is different to what happens when families split, where the new matriarch is usually about the same age as the existing one, a sister or close cousin who has similar experience and now gets the opportunity to lead on her own.

What all of this suggests is that elephants are making decisions based on relatively sophisticated information. Whether they leave or join a group is not a random matter, based on who happens to be closest, but an active choice. New matriarchs have to display certain leadership qualities, and, at least according to this study, there are times when purely social considerations of who you want to spend your time with, and who you want to rely on to lead, can overrule kinship alone.

[Photo by Bernard DuPont, from Wikimedia Commons.]

800th Synapsida

2026-10-04T13:09:52.344+01:00

Some primates, to make up for a scarcity of posts...

This will be the 800th post to be posted in this blog. That means it is once again time for me to take a break from doing anything original and take a look back at the last couple of years or so. There have been some changes in how I've been doing things since the last of these updates, but they're relatively minor, and posting has generally been pretty regular.

The most common topic in the last 100 posts has been animal behaviour, which has overtaken the usual frontrunner of evolution. It's a broad topic, of course, and the exact ranking will come down to the variability of how I happen to label posts, but it shows that it's not all taxonomy and anatomical adaptations here. In particular, there have been several posts about sociability of late, partly due to the discussions of how different dolphin species associate into pods. There have also, as usual, been several posts on diet and habitat, both topics that inevitably come up a lot when I discuss particular living animals, or even the way that they have changed over millions of years.

When it comes to the different types of mammal I have covered, the usual suspects remain the most common. Carnivorans top the list, with bears randomly getting above average exposure of late. Of course, the carnivorans are a broad group, since they include things like seals and walruses as well as the more obvious land-based animals. More likely, though, it's just that they are relatively charismatic, so that I suspect they will tend to be of more interest to readers.

It's probably for similar reasons that cloven-footed animals have also been common. They aren't the only large herbivores, of course, but there are far more species of them than of any other sort, so they tend to dominate in scientific studies. Rodents are also relatively popular in studies, partly due to being small, numerous, and (in some respects) comparatively easy to study, so they have had a fair amount of coverage too - although this has included a couple of relatively obscure groups, in the form of zokors and mole-voles.

There have been several posts on bats, too, which is probably down to me finding them particularly interesting animals, and to some of the research on them still being at a relatively early stage. (They're small, fly, nocturnal, and often hide in inhospitable and unreachable caves, so they're not exactly easy to study). On the downside, coverage of these groups has meant only two regular posts on primates, although one of them was an ape, which is unusual for the blog, and one just on a marsupial.

In terms of number of hits, the single most popular post in the last 200 was the post about speciation and coat colour in lemmings. This is, of course, somewhat biased by it having been up for a long time, and it's impossible to judge how popular posts that have only been up for a few weeks will eventually turn out to be - in light of which, I can note that post #699, on the nature of hair, has outstripped everything since, but obviously didn't feature as a heavy hitter on my last 100-post roundup.

With that in mind, I can say that, as of this writing, other especially popular posts have included those on dik-diks, Portuguese snow leopards, Oligocene Australia, brown bears fishing for salmon, spectral bats, and the evolutionary history of llamas. Some of these may be due to the vagaries of what people happen to type into search engines - related more to the title of the post than its content - but that's often the way this sort of thing goes.

I'll also note, for what it's worth, that the two posts on fossil birds have also scored above average on the popularity stakes. Maybe there's just not much palaeontological ornithology out there on the internet...

Many of the posts that did well also happen to be ones that I was particularly pleased with at the time, which hopefully tells me something. (The topic for most posts being decided on the day means that sometimes if I do decide something isn't working, it's usually too late to do anything about it). A few posts that were particularly interesting to write that ended up merely average in terms of readership include those on walruses, Ice Age rabbits, how to get hedgehogs to avoid lawnmowers, and the history and lives of Pleistocene cave bears. I'll also single out, because it's unusual for this blog, a post about the broad ecology of a fossil site in South Africa, covering the whole range of what has been found there, and what it can tell us about the climate and vegetation at the time.

My series on the dolphins of the world proved relatively popular, with a particular interest in the posts about deep-sea species and pilot whales, perhaps because those get relatively little coverage elsewhere. Of course, the series covered only the dolphin family proper, and therefore excluded both the porpoises and some of the stranger, freshwater, species that we might normally call "dolphins". Porpoises may prove tricky to do in my usual format, so I don't know how, or if, I will fit them in at a later date, but the others are a stronger bet for an eventual appearance.

After that, I moved on to the one of the few large groups of carnivoran mammals I had not previously covered, looking at both the viverrids, such as civets and genets, and the unique carnivores of Madagascar. This proved less popular, probably because few of them are familiar animals in the West, but they were necessary if I was going to eventually cover the full range of carnivorans. Relatively few remain on that front, with the mongooses the only major group left; like the porpoises, I'm not sure how I will cover them, but the smaller groups are lined up for a future series.

A similar theme of filling in the gaps lies behind my current series on antelopes that aren't either gazelles or bovines. While it's too early to judge, I don't expect this to prove particularly popular, and there is some degree of repetition within the subfamilies, with many species closely resembling one another. I'm currently about a third of the way through, and it will take some time to get to the impalas, which I know some fans of my other blog will have an interest in...

I'm not sure what the next mammal group will be once I've finished it; they could be primates, or they could be cetaceans. After that, however, it will be time to wrap up the carnivorans as effectively as I can, and I will probably be on that series by the time post #900 rolls around.

The posts on particular periods of Earth's past have a rather clearer future, since they follow a distinct pattern. In the last 100 posts, I have wrapped up the Oligocene, and I am now working on the Eocene, which is both a longer stretch of time, and further back in the past. It is necessarily going to be a long series, most likely with a section specifically on Asia, which I have tended to cover as an adjunct to Europe in the past. I would guess that it's unlikely to be completed within the next 100 posts. That's probably just as well since, while it isn't anywhere near the start of the mammalian story chronologically, it is where most of our detailed knowledge begins. There will be more once it's done, but not a lot more.

That's it for now, though. Next week, normal service will be resumed with... I have no idea yet.

[Photos by Alex Dunkel, K.A.I. Nekaris, Hans Hillewaert, Thomas Bresson, Ana Cotta, and "Lady of Hats", from Wikimedia Commons.]

Eocene (Pt 6): Gophers, Camels, and Lady Gaga

2026-09-26T18:05:01.685+01:00

Leptomeryx

World climate fluctuated during the Eocene epoch, but it was consistently warmer than it is today, including the lengthy Climatic Optimum, the hottest the world has been since the extinction of the non-avian dinosaurs. This naturally affected not just the weather, but where different types of vegetation were found. Much of North America was covered with subtropical forests, with at least some palm trees reaching as far north as Alaska, and temperate woodlands on the northern Canadian islands.

The animals you would have encountered in these woods would also have been unfamiliar, with most of the mammals not fitting within any family we would recognise today. Nonetheless, there were some exceptions.

Rodents were already in existence at the beginning of the Eocene, but became more varied as the epoch wore on. The first beavers appeared just before it ended, in the form of Agnotocastor from Canada. We don't know too much about this early form, other than it had yet to lose the third premolar tooth, which no living beaver possesses. However, the aquatic and tree-gnawing habits we associate with beavers today did not arise until much later, and we can imagine that it probably looked more like a muskrat than anything else alive today.

At the opposite end of the continent, the epoch also saw the appearance of the first gophers, in the form of Gregorymys from southern Mexico. While this is merely placed within the gopher family, not the subfamily to which all the living forms belong, some of its remains were discovered near fossilised burrows, suggesting that this habit, at least, was ancient.

Similarly, Cedromus, from Wyoming, may be one of the earliest known squirrels. The skull of one fossil was complete enough to allow a scan of its interior, revealing the size and shape of the brain. This showed the brain was, relative to body size, near the lower end for modern squirrel species, but not below it, while regions thought to be linked to visual orientation and agility were enlarged. Most likely, therefore, it was at least partially arboreal, like many of its modern relatives.

Other families present in Eocene North America failed to make it to the present day, or even out of the epoch. The sciuravids prospered during some of the hottest phases of the Eocene, disappearing as the climate settled down again in the Late part of the epoch. They seem to have been fairly diverse, with some species having been described as having a similar lifestyle to modern mice (a group that did not appear until much later), and others as being more arboreal, although there is debate as to how many species should really be included within the family, rather than placed elsewhere.

The name "sciuravid" suggests some relationship to squirrels, but this is misleading, since they appear, at least partly on the basis of their jaw muscles, to be closer to mice. On the other hand, what was probably the most successful group of Eocene rodents in North America, the ischyromyids, probably was over on the squirrel side of the great rodent family tree.

Ischyromyids are also known from other continents, are one of the few rodent groups to have originated before the start of the Eocene, and survived until about halfway through the following, Oligocene, epoch. They are, however, particularly well-known from North America, with a variety of different forms, united by typically having a long, but heavily built, snout, and a lower jaw that has the same general pattern as squirrels and their relatives.

They were, however, quite diverse. Ischyromys itself, for example, along with its relative Lophiparamys, is thought to have been arboreal, clambering about in trees and perhaps feeding on their leaves as well as more obvious food such as nuts. Paramys, on the other hand, although it may have been able to climb if it had to, was more likely to have been a scratch-digger, hiding in burrows. One estimate places the largest species of Paramys at up to 4 kg (8 lb 13 oz.) in body weight, which would also tend to count against tree-dwelling without more obvious adaptations, such as those in primates.

The cylindrodontids were another group of primitive rodents commonly found in North America, although it's possible they originally appeared in Asia. Relatively short-snouted, they ranged in size from mice to ground squirrels, and have been found in areas that were once subtropical forests, although, with few remains other than skulls, their exact lifestyle remains unclear. Examples include Tuscahomys from Wyoming and Mississippi.

There were, of course, many larger animals living alongside the rodents, and some of them also represent the start of lineages with which we are familiar today. Perchoerus is better known from the following, Oligocene epoch, but the oldest species lived in what is now the northwestern US during the last few million years of the Eocene. Long thought to be a peccary, it is now regarded as a close relative of the last common ancestor of the peccaries and pigs, placing it near the very base of the suine family tree. It was, however, far smaller than any modern example of its kind, similar to a modern house cat, and probably would not have looked much like a pig in life.

Given their present-day distribution, it is perhaps surprising that camels first evolved in North America. It was only much later that they spread through Asia to North Africa, and separately to South America, where they gave rise to the llamas.

Quite what the oldest known fossil camel is is complicated by the common issue in palaeontology of deciding where to draw the line between "camel" and "not-quite-yet-a-camel". Taking a broad view, then Protylopus is the likely best bet. This lived during the Early Eocene, indicating an unusually early branch within the cloven-footed mammals in general. It would, however, not have looked much like a modern camel (or llama). For one thing, it lived in damp subtropical forests eating soft leaves, so it was hardly desert-adapted. Furthermore, it had four toes on each foot, probably with hooves rather than foot pads. It also only stood about 30 cm (12 inches) tall at the shoulder...

Animals that are less ambiguously camels came along not much later, during the Middle Eocene. Poebrodon is one of the earliest examples, living from Wyoming to southern California during the Middle Eocene. While still not desert-dwelling, the group had begun to diversify by the end of the epoch, with the Late Eocene Stevenscamelus from Texas being the earliest known "narrow-snouted camel", a group of browsers on leafy bushes that survived in North America until well into the Miocene.

Other cloven-footed animals of the time belonged to no family that we would recognise today. Bathygenys, which lived from Texas to Montana in the Late Eocene, was an oreodont, with four hooves on each foot. This was a group that would become much more successful in the following two epochs, reaching relatively large size and adapting to an increasingly dry and prairie-like habitat as the world's climate changed.

Early entelodont "hell-pigs" crossed over from Asia in the Late Eocene, probably in the form of Brachyhyops, which lived from Texas to Saskatchewan, but is also known from older deposits in Mongolia. Anthracotheres, which somewhat resembled hippos, also originated in Asia before crossing over the Bering land bridge to North America. The earliest-known example on the continent is Heptacodon, whose oldest definitive fossils hail from Texas, but which also reached as far north as Oregon, and possibly Canada. Compared with others of its kind, it had an unusually short, broad snout and large canine teeth with edges that flared out to the sides.

The protoceratids of later epochs are best known for the unusual property of having three horns, at least in the males; two in the usual place and a third one near the tip of the snout. Eocene forms, however, such as Leptoreodon and Pseudoprotoceras, were hornless, although they would otherwise have resembled small deer. The family was unique to North America, and may be most closely related to either the camels or the true ruminants, although they do not fall directly into either group.

The hypertragulids may have actually been true ruminants, although they are sufficiently primitive that it's difficult to tell. It's perhaps more likely that they are outside the living groups, although likely more related to ruminants than to camels. The group is currently considered to be unique to North America, although close relatives also lived in Asia, where they likely first originated.

An unusual feature of the hypertragulids is that the front feet still had five toes, although one was already vestigial; the hind feet had the usual pattern we see in cloven-footed mammals today. They were also among the first cloven-footed animals to develop the "selenodont" pattern of having crescent-shaped cutting surfaces on their molar teeth, improving their ability to chew vegetation, which may have been a factor in the subsequent expansion of the larger group. Examples include Hypertragulus itself, which is found from Oregon to Mexico, and Hypisodus from Montana and Colorado. Both were small animals, resembling today's muntjacs, and likely had a similar browsing diet.

Leptomeryx was similar, although it lived slightly later in the epoch than the earliest hypertragulids. Estimated to have weighed around 3 kg (6 lb 20 oz.) it, too, had four functional toes on the front feet and two on the hind ones. A significant difference is that, whereas the hypertragulids had enlarged canine teeth, similar to those of modern musk deer, they were reduced or absent altogether in Leptomeryx and its relatives. They probably lived in open woodlands or on the edge of denser forests.

Gagadon, which was only the size of a rabbit, is among the most primitive of all cloven-footed mammals in North America. It lived in Wyoming during the Early Eocene, and belongs to an obscure family that may or may not be related to the distant ancestors of camels, but still retain the full set of mammalian teeth, including the upper incisors that are replaced by a toothless chopping board in almost everything else. They were likely fast-running animals, hiding in forest undergrowth and feeding on soft leaves.

It is, however, perhaps more famous for its full scientific name, Gagadon minimonstrum, which translates, very roughly, as "Lady Gaga's little monster". Because modern palaeontologists are getting young enough not to name everything after The Beatles or Motorhead...

[Photo by "ghedoghedo" from Wikimedia Commons.]

All the World's Antelopes: Waterbuck and marsh-dwellers

2026-09-20T17:34:36.795+01:00

Kob

One of the features of the reduncinine subfamily of antelopes, as opposed to most of the other groupings, is that they require ready access to standing water. Many of them, such as the reedbucks, are grassland animals, avoiding the driest areas, but otherwise living in plains and mountains, only retreating to riverbanks and marshes during the dry season. Others may, if anything, be even more tied to the water.

The kob (Kobus kob) lives across the savannah belt south of the Sahara, from Senegal to Uganda. It is said to never be seen more than 10 km (6 miles) from standing water, and usually much less. The unusually blunt scientific name comes from two different authors, with Charles Hamilton Smith having added the first half in 1840, after the animal had been originally described (as Antilope kob) by Erxleben much earlier, in 1777.

It's a moderately-sized antelope, standing between 85 and 100 cm (2'9" and 3'6") tall at the shoulder. The coat is golden to reddish-brown, with white underparts and white markings on the face. While all males become darker as they age, this is especially true in the easternmost subspecies, where they eventually become near-black, only retaining the white markings; there were proposals to split this off as a separate species in the early 2000s, but, absent clear genetic evidence, this is not widely accepted today. As with other reduncinines, only the males have horns, and these are lyre-shaped, reaching about 50 to 60 cm (20 to 24 inches) in length when fully grown.

It lives on grassy floodplains and other open habitat, avoiding forest, although it may retreat to lightly wooded areas in the dry season. When the rains come, the plains become lush with grass, and the kob feeds on little else, but at drier times of the year their diet is wider, with some studies suggesting about half of it comes from herbs and tree leaves.

Kobs are only moderately social; they gather together in large herds of 50 individuals or more, but these do not seem to be permanent associations. Indeed, they are most commonly seen when either food is especially abundant at the start of the rainy season, or when access to water is limited during the dry; in between, they gather in much smaller groups, of perhaps no more than five each. There is also evidence that herd sizes have decreased over recent decades due to pressure from hunting, although the species is widespread enough and lives in sufficient protected areas that, as a whole, it is not considered to be threatened.

Their breeding habits may have changed over the same time frame. Adult males live apart from the females, in small bachelor herds when young, and then largely on their own once they are old enough to breed. The natural habit of kobs, historically, seems to have been "lekking" - the male defends a small patch of mating ground and attracts the females to it. As population densities have dropped however, it has become more viable for the males to defend larger territories, focussing more on deterring rivals from entering it than attracting mates who already live there.

This has the advantage, from the male's point of view, that he can control access to the females, and be sure most calves are his. Where lekking still occurs, the female can simply wander from one patch to another nearby, mating with however many males she feels like - up to nine partners have been recorded within a close timeframe.

Such defence consists largely of posturing, with the traditional lekking behaviour often consisting of the male standing somewhere prominent such as the top of an anthill - something easily adapted to intimidating other males. While this seems sufficient in most cases, rare outbreaks of violence do occur, with the males clashing with their horns. Presumably they could have done the same when population densities were higher, and they must have done so on occasion, but the effort of fighting off too many nearby rivals may not have been worth the trouble.

Breeding occurs throughout the year, although births are more common around the start of the dry season. The pattern after birth is the same as that for other reduncinines. The infant remains concealed in long grass for the first six to eight weeks, being visited periodically by its mother for feeding. It is only after this that it begins to follow its mother around, socialising with other nearby animals.

Lechwe

In contrast, the lechwe (Kobus leche) is a true marsh-dweller. They live only in wetlands, spending much of their lives wading about in shallow water, although they will also utilise nearby lush grasslands. They prefer to have a good view of their surroundings, and so avoid woodlands, but their watery habitat also discourages lions from pursuing them. When this does happen, they bound through the water to escape, landing all four feet on the ground at once. While they prefer that the water they live in be no deeper than 50 cm (20 inches), they can also swim in deeper channels and will do so if they have to.

These habitat requirements inevitably mean that lechwe have a discontinuous population, split apart from one another by the vagaries of geography, since marshes are rarely that extensive. They are found primarily in Zambia, but with significant populations in Angola, Botswana, the DRC, and the Caprivi Strip of northeast Namibia. (Namibia is largely arid, but the Strip is much less so, since the whole point of it was to allow German traders access to the Zambezi).

Lechwe seem to be pure grazers, eating little but long, lush marshland grass. Exactly which grasses they eat may vary throughout the year, as waters rise and recede with the seasons. In winter, they also eat sedges, but their restricted habitat seemingly gives them little opportunity to eat much else even if they wanted to.

They have a similar build to kobs, but are slightly larger, with the largest males reaching 115 cm (3' 9") at the shoulders, and typically have a redder coat. Perhaps the clearest distinction is in the horns, which are about the same length as in kobs, and have a similar ringed structure, but are straighter and splayed outwards rather than curving back.

The herd structure is highly unstable, with membership of groups changing over the course of just a few hours. Nonetheless, lechwe can gather in immense herds at times, with hundreds or even thousands of individuals feeding in the same area. While most antelopes rest during the heat of the noonday sun, lechwe only do this during times of the year when the water level is low, apparently cooled enough by their partial immersion not to be concerned otherwise. There is some evidence that they may head onto drier neighbouring ground at night to graze there, but detailed studies are lacking.

Since population densities can be high in the limited areas where they live, male lechwe still stick to the lekking habits that kobs have largely abandoned since the 1980s. Males maintain small territories on the water's edge, from which they seek to attract mates from the surrounding marshland. Often, this means that they spend their time on small islands, which can potentially be very close to one another. Territories are typically about 0.06 km² (15 acres) and can be much smaller, with the actual lekking patch being no more than 10 metres (30 feet) across. If male intruders are not intimidated away by their mere presence, the defender can chase and fight them, pushing with locked horns.

There is a distinct breeding season, such that calves are born at the start of the dry season, just as the waters begin to recede and reveal stands of lush grass. Infants are hidden in stands of reeds, the marshy habitat being ideal for such concealment so long the ground is not too flooded.

Nile lechwe

As with kobs, and many other antelopes, there have been proposals to split the lechwe into multiple species. Today, however, only one of these distinct species is widely recognised: the Nile lechwe (Kobus megaceros). This lives around the White Nile and its tributaries in South Sudan and neighbouring parts of Ethiopia in habitats essentially the same as those of its southern relative. They are, however, reported to avoid areas with heavy growth of papyrus, presumably because these tall sedges obscure their view of any predators thinking about taking a dip.

Visibly, the Nile lechwe is clearly distinct from its southern cousin. Females are a drab ochre colour, lacking the rich red of the common species, but the males are much darker, with a thick shaggy coat that emphasises their already much larger size. Unlike the females, they have distinct white markings, likely to make them look attractive to potential mates. As the second half of their scientific name suggests, their horns are much larger than those of regular lechwe, having a more lyre-like shape and reaching up to 87 cm (34 inches).

Their marshy habitat results in similarly large congregations as well, although there are some reports of a distinct social hierarchy among the females that seems less evident in the unstable grouping of the southern species. Males compete for access to the females, typically with brief bursts of violence, wrestling with their horns, and sometimes with each animal trying to hold the other's head underwater until it submits. That's normally effective, but in captivity, where the options for escape are limited, the dominant animal can be so enraged by the continued presence of its rival that the latter may die from its injuries.

On the other hand, dominant males ignore other males that have yet to develop the white markings on their face that come with full adulthood. Significantly, the development of this pattern seems to be delayed in subordinates living in captivity, which rapidly change colour if a larger male dies and leaves a vacancy.

Unfortunately, South Sudan is not a good place to live at the present, and that's as much true for antelopes as for humans. While expansion of farmland may be a risk to Nile lechwe, the larger one is probably poaching, both by illegal hunters in a country with limited countryside law enforcement and active predation by food-starved armed militias and their opponents in the official army. Should the current civil war come to an end, there are plans to construct a canal that would divert water to agricultural land to the north, which would be further bad news for the Nile lechwe, and other animals and plants relying on the local wetlands.

As a result, the Nile lechwe has been listed as an endangered species since 2008.

Waterbuck (female)

The same cannot be said for the waterbuck (Kobus ellipsiprymnus), which is one of Africa's most widespread antelopes. They are found across all of the savannah regions of the continent, across North Africa from Senegal to Ethiopia, and from there south all the way to South Africa. While not immune from hunting, any population decline is, so far, thought to be insufficient to pose any threat to the species.

They are larger than kobs or lechwe, with males standing up to 136 cm (4'6") at the shoulder and weighing up to 265 kg (580 lbs), although females are notably smaller. They have a shaggy, dark-grey coat smeared with an oily secretion that may help repel water, and various white markings, most notably a "bib" on the throat and a a ring pattern around the rump that may be used in social signalling. The horns lack the double curve seen in kobs and lechwe, curving out and upwards, and reaching 92 cm (36 inches) in length.

They live in grasslands, much as kob do although, as the name suggests, they are also closely associated with water, rarely straying more than 1 or 2 km (roughly a mile) away. While they feed on grasses for much of the year, they will switch to a wider diet in the dry season, and the northern subspecies (although not, apparently, the southern one) regularly wades out into shallow water to graze on sedges or other water plants where they peak above the surface.

Females live in herds of up to 20 members, although more break up into smaller groups during the wet season. As with their relatives, however, membership of these herds is very fluid, varying from day to day to such an extent that there is no indication of any social hierarchy within them; it would probably be too much effort to establish one when you would have to reassert your dominance over newcomers several times a day. While adult males are solitary, younger ones live in bachelor herds of about five members, and these do seem to be stable, and moreover, to develop a dominance hierarchy even before they are old enough to breed.

As a result, females range over territories as large as 6.5 km² (2½ square miles), while males defend small patches of high-quality grassland of no more than 0.9 km² (220 acres). They do this by posing in such a way as to show off the length of their horns, resorting to violence only if an incoming male refuses to back down, as most do. There is, nonetheless, evidently competition for such prime areas, and only around 20% of males will ever get to hold a territory during their lifetime. At any given time, however, around 8% of males hang about on the edges of the territory of a more dominant counterpart, sharing in its defence while not competing for females, probably in the hope of getting to take it over in due course.

Puku

The puku (Kobus vardonii) lives in much the same region as the common lechwe, in Zambia, Angola, Botswana, the southern DRC, and parts of Malawi. While it, too, is reliant on water, it is not a true marsh-dweller, preferring to graze at the margins of wetlands rather than wading into them. This allows the two to live side by side without competing, given that they otherwise have very similar diets and general requirements. Equally, their diet is different from that of other antelopes living in the area (such as sable antelope), with the animal eating different grasses, perhaps because of their preference for not wandering far from water.

Puku are, marginally, the smallest of the species in their genus, with the largest males not exceeding 85 cm (2' 9") at the shoulder, and females rather smaller. Dominant males are said to have visibly muscular necks, something that must stand them in good stead while horn-wrestling. Both sexes are a golden-yellow colour, appearing very similar to the kob, but distinguished from it largely by the absence of black markings on the front of the legs.

While they have not been studied to the same extent as the other species, their behaviour seems largely similar. Herds only exceed 20 members during the dry season, when they huddle close together around remaining water sources, and males are either solitary or live in small bachelor herds. Females move about, but not across an especially large territory, while dominant males defend small patches of high-quality land, using a two-tone whistle to warn off would-be intruders as well as visual displays and, if necessary, aggression. Female puku often travel in mixed groups with impala, at least for short periods, sharing in mutual defence without competing for the same grasses.

That brings me to the end of the reduncinine antelopes, a relatively small subfamily in terms of number of species. The largest subfamily is that of the gazelles, which I have covered elsewhere, but the second largest is far less well-known, consisting, as it does, of mostly small and elusive species. It is to that that I will turn next.

[Photos by "flowcomm", Ian Restall, Tylwyth Eldar, Derek Keats, and Timothy Gonsalves. Cladogram adapted from Bibi, 2013.]

Dishonest Bears

2026-09-13T16:34:37.917+01:00

Mammals use a variety of means to communicate with one another: vocal, scent, and visual. Even those that are mostly solitary need to do this from time to time, whether to mark out their territories as a warning to others or to attract mates.

Often these signals need to convey more than the basic message, but also provide some information about the animal that left them. This often includes physical fitness, whether to intimidate potential intruders or to advertise oneself as a sexual partner. At close range, this can be achieved through such things as growing huge antlers, proving that you have the physical capacity to waste resources on something that's otherwise pointless. But, at longer range, a simple indicator of size may be all that's required.

We see this in vocal signals, where a deep, booming call might, for example, indicate the general size of an adult male seeking a mate. But it can apply to scent marking, and even to some visual signals.

For instance, when mongooses and civets leave scent marks, they do this by performing a handstand, spraying scent and/or urine onto a tree or other vertical feature. This unusual posture allows them to place the mark up as high as they can physically manage, an honest indicator of how big they happen to be. They can't, after all, place the mark higher than they can reach, so, like the deep call of a stag in rut, it's genuinely useful information to others of their kind.

With any such signal, there are payoffs to be considered. There's the obvious balance between how much effort it takes to leave the mark or make the call, and how big the benefit you expect to receive is. But there's also a question of honesty. Can the signal be faked somehow, giving an illicit benefit to the dishonest animal?

Let's take those mongooses again. Presumably, they didn't start out by performing handstands for the sake of it. They probably left marks on trees, with those who were bigger seeming more intimidating or sexually attractive to passers-by coming across the mark. But, over time, those who could manoeuvre themselves into a position allowing them to place the mark higher benefited from 'exaggerating' their size. Evolution took hold, until everyone was balancing upright on their forepaws, and the mark was as high as they could possibly make it - an honest signal once again.

Absent such long-term changes, however, a signal from one animal to another needs to be taken as reliable, or there's little point making it. If dishonesty is an option, it needs to be rare enough that, at least most of the time, the intended recipient doesn't consider it. So long as it's reliable significantly more often than not, the communication method can remain in use even if a few individuals benefit by cheating the system.

Brown bears (Ursus arctos) have long been known to use scent marks as a means of communication. Their usual method of leaving these marks is to stand up on their hind legs and rub their back against tree trunks. This leaves behind secretions from the sebaceous glands on their back, shoulders, and neck that, because these glands become enlarged in the presence of testosterone, provides useful information about their sex and virility. Bears also have regular anogenital scent glands and can also leave marks by urinating or rubbing their feet on the ground.

However, in just the last few years, it has become apparent that brown bears also leave visual signals. They do this by debarking trees with their claws, a behaviour previously attributed to leaving scent marks. That's undeniably a part of it, and it's only done by adult males during the mating season, so the reason for it is fairly clear. But it turns out that the bright, visual signal of leaving patches of bare wood on the tree is also an important part of the message.

Specifically, it gives passing females an idea of how large the male is, by virtue of how far he can reach.

Assuming, of course, he doesn't try to cheat by climbing a short way up the tree first. The question is, how often does this really happen, and is there any real benefit to the male bear in trying to do this, given that he'll inevitably be found out when the female sees him in the flesh? A recent study conducted in the Cantabrian Mountains of northern Spain aimed to find out.

The researchers set up camera traps at trees known to be used by the local bears. (These were, incidentally, once considered a distinct subspecies and, while that's no longer true, they are locally endangered, with an estimated total population of just 130 in 2009). To encourage the bears to cheat, they provided piles of stones or wooden platforms close by the trees that they could clamber on top of, allowing them to reach higher up the tree than they could while standing on the ground.

Over the course of the study, the researchers were able to capture 164 incidents of bears marking trees and it turns out that, on the whole, they did so honestly. Even when presented with a viable method of cheating, the bears only attempted to use them 4% of the time. This is good news for other bears relying on the height of tree markings as a measure of who else is in the area; far more often than not, the information is reliable.

This is what we'd expect of a good communication method, allowing the recipient to trust what they are being told. But, even so, it's worth noting that some bears were "dishonest" about their size, in a few cases even climbing trees without the platforms, demonstrating that this, at least occasionally, a natural behaviour, not one they need to be coaxed into performing.

But, here, one can wonder what the point is. It's exclusively a male behaviour, because the females don't bother to indicate their size in this way. They don't need to, because females don't compete for mates, and rarely come into conflict with one another. There's no reason to lie about your size when nobody cares about it anyway.

Among those bears who were apparently being deceptive, the majority were subadults or otherwise smaller (and typically younger) than average. Full-grown bears are apparently confident enough in their prowess that they don't need to exaggerate it, even assuming they can do so as easily as smaller bears - which is likely, but perhaps not a given. But if those smaller bears did come across a female, then, like somebody using a fake Tinder photo, they would immediately be found out.

It's possible that any opportunity at mating is worth the risk, but it's perhaps more likely that this is merely a secondary benefit. It may be more important to the bears that the markings act as intimidatory signal to other, larger males. A full-grown male, seeing that someone of similar size to (or larger than) himself is in the area, might decide it isn't worth the trouble to look for females there, and run the risk of fighting the mystery male.

Avoiding such fights might well be worth it for subadult or smaller males, giving them an incentive to occasionally lie about their size - so long as they don't do it so often that nobody believes them. This is, of course, just speculation, since the study merely shows that it happens, not any definitive reason for it. Still, something similar has been proposed for giant pandas, which seem to avoid areas where fake scent marks have been placed artificially high on trees, as if left by some mysteriously large, potentially hostile, panda.

With 96% of the bears in this study providing a genuine signal of their height, it would seem that honesty is often the best policy. But, every now and then, one of them plays the system, making himself out to be tougher, and perhaps sexier, than he really is.

[Photo by "Byrdyak" from Wikimedia Commons.]

All the World's Antelopes: Reedbuck and Rhebok

2026-09-06T15:53:31.926+01:00

Bohor reedbuck

Quite where, within the larger bovid family, the reedbucks belong was long a matter of contention. They are medium-sized antelopes, tending to prefer habitats with plenty of water, distinguished by the fact that not only their visible horns, but also the bony cores on the inside, have transverse ridges running round them. The detailed structure of their teeth has some resemblance to that of the true bovines (that is, cows, bison, and the like) but it's hard to see that as anything other than parallel evolution.

The most widely followed scheme in the late 20th century placed them with the grazing antelopes, such as sables and their kin, but even then there was a suspicion that this was only because nobody knew what else to do with them. Once we were able to do detailed genetic analysis, it turned out that they are pretty much in a group of their own, not especially close to anything, having diverged from the ancestors of the true grazing antelopes before that group diverged from the goats. Our best guess is that this happened between 16 and 14 million years ago; there are antelopes with longer lineages, but not many.

The first species of reedbuck to be described was the one for which the entire subfamily, the Reduncinae, was subsequently named. Its most common name today is the Bohor reedbuck (Redunca redunca), although many others are also used, even if we only count the English ones. When Pallas first described it in 1767, he said that it lived in what would now be Senegal, but it's much more widespread than that - which goes some way to explaining the multiple different names.

In fact, it's found along a wide belt of land south of the Sahel, from the Atlantic coast in Senegal, Gambia, and Guinea, across all the way to central Ethiopia, and then southward through the East African savannah as far as southern Tanzania. At least five different subspecies have been identified across this wide range; it has been proposed in the past that four of these should be considered distinct species, but the modern consensus is that there is no strong evidence for this. (Which, in fairness, doesn't mean it's not true, just that we have no reason to suspect it is).

The bohor reedbuck stands between about 65 and 85 cm (2'2" and 3'9") in height, with males larger than females. The coat is a fawnish yellow, with clear white underparts and, in some subspecies, black markings on the front of the legs. Their hair has been described as "greasy", due to an unusually large number of sebaceous glands, secreting a lubricating and water-repelling oil. Like other reedbucks, only the males have horns. These are curved, with distinct ridges that are especially large towards the base; in the largest individuals, they can be as much as 40 cm (16 inches) in length.

They are grassland animals, actively avoiding forests and woodland. It does, however, require nearby surface water, so it rarely ventures too far from rivers or other sources, and often moves into marshlands during the dry season. For the most part, this means that Bohor reedbucks are found in lowland areas, they can be found in some mountainous regions as high as 3750 metres (12,300 feet).

As one might expect for a grassland antelope, they are very much grazing animals, with at least 90% of their diet consisting of grass. They are active both day and night, grazing in areas of short grass for four bouts a day, but retreating into areas of much longer grass to escape the heat of the noonday sun. Here, they can lie down and allow the plant life to conceal them, doubtless aided by their coat being roughly the colour of dried grass. They can travel up to 6 km (3½ miles) a day, but don't usually bother unless they are having difficulty finding good places to graze.

They are not particularly sociable animals. While large aggregations can be seen around riverbanks or marshy areas where food is particularly plentiful, herds rarely number more than five individuals, and around half the females and almost all the adult males live alone. Each male defends a territory with an area of 20 to 30 hectares (50 to 75 acres) but, unlike many other species, they don't seem to actively mark its boundary, instead warning off potential rivals with a whistling call.

Males gather a sort of loose harem of up to five females, but this isn't the sort of grouping we'd normally think of since the females don't often stay close to each other, let alone the buck. There does not seem to be any particular breeding season, although it's possible that mating is less likely when young would be born at the height of the dry season. The male entices receptive females with a noise that is said to sound like a toy trumpet, as well as the usual flehmen gestures seen in many hooved animals.

Females give birth to a single calf, but due to there being only limited studies on the species, and mothers being rather good at hiding their children, we know little about their development. We do know that territorial males will drive away any young males as soon as they start to grow horns; these often end up in bachelor areas that nobody else wants, in between the more preferable territories, at least until they become old enough to set up their own.

Southern reedbuck

The southern reedbuck (Redunca arundinum) lives, as one might expect, further south, although there is some overlap in Tanzania. It is found across the savannah belt of southern Africa, from Angola in the west to Mozambique in the east, extending as far south as northeastern South Africa and into the southern reaches of the DRC in the north. As with the Bohor reedbuck, there was a move to split it into two species in the 2010s, but this didn't come to anything.

Although there is considerable overlap, the southern reedbuck can reach significantly greater sizes than its northern relative, with some males apparently having a shoulder height as great as 150 cm (4' 11"). They otherwise look much the same, but with a drabber tone, and with black markings on the forelegs being more common, and sometimes present on the hind legs as well. Like the Bohor reedbuck, they have a glandular area beneath the ears that is covered by hair, but that becomes visible as a black patch when it is secreting (for a purpose that remains unclear).

They live in grasslands, with the vast majority of their diet consisting of grass, but they are more willing to venture into woodlands than their northern kin, being more of a savannah animal than a true grassland one. They require fresh standing water and retreat to riverbanks during the dry season, when they are also more likely to resort to eating herbs due to a lack of fresh grass. They are also willing to wade into water to feed, although they prefer to avoid anything deeper than about 20 cm (8 inches), so they're hardly aquatic.

Like the Bohor reedbuck, they are unusually antisocial for a "herd" animal. Even when they are seen gathering into groups, the membership of these groups is constantly changing, with no fidelity to their partners. Aside from females with their young - which stay together for almost a year - this means that, socially speaking, they are mostly solitary, even if they tolerate one another's presence and happily feed together. Males become territorial only around the breeding season, when they drive away rivals, although the exact way that this is arranged seems to vary between populations, probably based on how many reedbuck a given area can easily support.

There has been more research into the reproductive habits of the southern reedbuck than its northern counterpart, primarily in South Africa. As a result, we can say that infants remain hidden for the first six weeks of life, pressing themselves close to the ground in long grass. The mother stays within 200 metres (yards) but only visits once a day, usually at around noon, to provide milk, after which the fawn moves to a different spot, never reusing the same one twice. This is all to conceal the infant from predators, but should it fail, the mother is highly protective and aggressive, having been seen fighting off baboons.

Mountain reedbuck

The mountain reedbuck (Redunca fulvorufula) is of similar size to the Bohor species, but is grey in colour over most of the body, with a distinct reddish tinge to the hair on the head and neck. The glandular patch beneath the ears is hairless, and thus more regularly visible.

It is unusual in that it lives in three completely different parts of Africa, with no connection between them. There is no clear indication of how this could have happened, but it does make the suggestion that there are three different species at least a little more plausible than with the others. But then again, not necessarily, since it has been suggested that they once occupied a much wider area, before being split into three as a result of human activity.

One population lives in eastern South Africa, Lesotho, and Eswatini. A second lives in the northern part of the Great Rift Valley in Ethiopia and Kenya, with some extension into neighbouring countries, while the third, and by far the smallest, lives way over in the west, on the border between Nigeria and Cameroon.

What these areas have in common is, as one might expect from the common name of the antelope, mountains. Unlike the other species of reedbuck, they avoid flat terrain and lowland areas, never venturing below about 1,500 metres (4,900 feet) and often living twice that high up. While they do like grasslands, in their case these are montane grasslands, with steep slopes and rocky landscapes where most other hooved mammals will not venture (there being no goats in this part of the world), and predators are hopefully unable to pursue them.

Diet, habits, and social organisation are all broadly similar to the other reedbucks. Females travel in groups of up to eight, but don't stick with any particular group for long, apparently seeking safety in numbers rather than forming any long-term bonds with their fellow travellers. Males are solitary, picking territories on steep terrain where females are more likely to visit, their boundaries often marked by physical features. Although the glands under their ears are more visible than in the other species, they, too, do not use them for marking their territory, warning off rivals with whistling calls and, if necessary, aggressive posturing.

Since 2017, the mountain reedbuck has been considered an endangered species. This is not because they are especially rare - although they certainly aren't common - but a result of research showing that the South African population crashed by as much as two-thirds in the first 15 years or so of the 21st century. If that were to continue, it would obviously not be sustainable, and the two northern populations are much smaller, representing only 10% of the total between them. While trophy hunting may be a part of this, it's more likely that the expansion of agriculture and cattle ranching in the region has played the largest role.

Rhebok

The reedbucks are, however, not the only members of their small subfamily. One of the others is the rhebok (Pelea capreolus), sometimes called the "grey rhebok", despite the fact that they don't come in any other colour. The similarity in the name is a coincidence, since "rhebok" was originally a misspelling of the Dutch word "reebok", which means "male roe deer". (It was this latter spelling that influenced the sportswear brand, apparently because they came across it in a South African dictionary). Presumably, they reminded early European settlers of the animal from their homeland.

Rhebok live in the coastal and highland regions of South Africa and Lesotho, but not the arid interior. They are about the same size as reedbucks, with relatively thick grey hair and only a few faint markings. The horns, present only in the males, are straight and narrow, with the rings restricted to the base. Distinctive features include a comparatively large and bulbous rhinarium (the hairless, black bit on the end of the nose) and long, narrow, almost rabbit-like ears.

Although they can be found at low elevation in some coastal areas, for the most part, rhebok inhabit hilly or mountainous terrain. They prefer areas of open woodland, often just below the treeline, and avoid both dense forest and tall grassland. Together with their liking for steep slopes, this indicates that they are far more concerned about being able to see predators coming than they are about the possibility that the predator will also see them - something that makes sense if you're good at rapidly fleeing into inaccessible areas. (In contrast, reedbucks just duck down and hope not to be noticed).

It is also not regularly associated with standing water, as all other members of the subfamily are. The presumption is that, when this part of Africa began to dry out in the Late Miocene, all of the other species retreated to the few remaining places with a good water supply, while the ancestors of the rhebok took the opposite approach and evolved to do without.

It was long thought that the rhebok, like true reedbucks, was a grazer, but when scientists finally got around to analysing their dung, they got something of a surprise. Rhebok eat relatively little grass, with some studies showing that over 95% of their diet consists of leaves from shrubs and other low-lying, but non-grassy, plants. Paper daisies and Aspalathus legumes seem to be their favoured foods, although the details may vary across their range, depending on what is available.

Like true reedbucks, they are active both day and night, but they show less of an aversion to the noonday sun, possibly because many of them live at cooler altitudes. Similarly, when they do rest, it isn't in long grass, but in areas with a good view of the surrounding countryside.

Their social organisation is also quite different. Rhebok live in harem groups, with a single male, up to five adult females, and however many young and subadults may still be travelling with them. It is only those adult males who have yet to secure a harem that live on their own. Each of these herds occupies a distinct territory, typically around 65 hectares (160 acres), which the male marks with his dung, driving off any potential rivals. When travelling, however, he is at the back, with a female leading the way, so it is she who decides where to feed.

There is a distinct breeding season, but when it happens depends on which half of South Africa the animal lives in, something that has been attributed to the differing seasonal rainfall patterns across the country. Females treat their infants in much the same way as reedbuck mothers, the first few weeks after birth being the only time in a rhebok's life when it actually will try to hide in long grass or other dense vegetation.

The rhebok is unusual amongst the reduncine antelopes, sufficiently so that it is sometimes placed in a separate tribe within the main grouping. There are, however, five other species in the subfamily and next time, I will look at those.

[Photos by Yathin S. Krishnappa, Nathan Earley, Diego Rubolini, and Bernard duPont, from Wikimedia Commons.]

Hippos in the Tiber

2026-08-30T16:31:35.417+01:00

The hippopotamus (Hippopotamus amphibius) is an iconic African animal. While their distribution is very patchy, in part due to their reliance on large waterways, they are found across essentially the whole of Africa south of the Sahara and north of the Kalahari and the South African veldt. A second, endangered, species belonging to the same family, the pygmy hippo (Choeropsis liberiensis), lives only on the southern coast of West Africa, between Sierra Leone and Côte d'Ivoire.

But hippos were once common in Europe and southern Asia. In the case of Europe, for example, we have fossils from Portugal to Greece, and as far north as the UK. Nevertheless, hippos have never been especially diverse, at least in comparison to groups such as deer or pigs, and they are grouped into no more than around six widely accepted genera. This includes the two that are still with us, and we don't have a large amount of information on three of the others.

While some others were isolated on islands, there are only two widely accepted species of hippo that lived in mainland Europe, both doing so in the warm gaps between the Ice Ages. One of these is the common hippo of today, which ranged much further north than that it does now. The other is the "ancient hippo" (Hippopotamus antiquus), which was very widely ranging, being found across both western and southeastern Europe, as well as in Turkey, and perhaps as far east as the Caucasus.

This is not to say that other fossil species of European hippo have not been named down the years. Some of these were on the basis of fragmentary material that is now thought insufficient to identify anything, while others have been determined to be too similar to either of the known species to be separated out. One possible exception is the "Tiberian" hippo (Hippopotamus tiberinus) which was named in 1991 based on a fossil from Italy. More material was found in Germany in later years, so there's little doubt that it existed as something identifiable, but today it's generally regarded as a relatively late example of H. antiquus, rather than a distinct species.

The oldest known fossils of the ancient hippo date back about 2 million years, to roughly the start of the Ice Ages. At this time, it lived in the south, with fossils known from Spain, Italy, and Greece. So far as we can tell, it first headed north of the Alps just over 1 million years ago, passing through France and Germany to reach the Netherlands and southern England.

As Ice Ages came and went, it would have been forced back south from time to time, and the very last known remains are from Portugal and Italy. These both date to around 400,000 years ago, slightly later than the oldest known European fossils of the modern species, so that the two may have briefly lived side by side. The modern species then replaced it, finally leaving Europe either at the start of, or perhaps even during, the Last Ice Age.

Physically, the ancient hippo would have looked similar to the modern sort, but it had a narrower head and longer snout, and moreover, was much bigger, perhaps around twice the weight of the modern species at just over 3 tons - similar to a female Asian elephant or the largest male rhinos. This is roughly tied with the African species H. gorgops for the honour of "largest hippo ever", although there's enough uncertainty in estimating the weight of an animal for which you only have a skeleton that it's hard to be more precise.

Most fossils of the species, however, date back to the Early Pleistocene, and less is known about how it might have changed later on, which might have a bearing on the exact status of the Tiberian hippo (which might arguably be a subspecies, although it's never been formally named as such). A recently published study, however, takes a detailed look at remains from a site in Italy that may help to fill in some of this gap.

The fossil in question consists of a jawbone and part of the leg and was discovered in a cliffside at Ortona, on the Adriatic coast. It has been dated to between 790,000 and 680,000 years ago, and was once a sand bar along one edge of a lagoon. The same site has also provided fossils of red deer and the straight-tusked elephant (an extinct relative of the modern African species). The jawbone is perhaps the most significant part, its slender shape confirming that it belongs to H. antiquus, as we would expect from the age.

However, by comparing it with other fossils uncovered elsewhere, the researchers were able to identify two distinct forms of the species, an early one, and a larger one that lived later on and that matches the so-called Tiberian hippo.

As to how these forms related to each other, there are a couple of theories. The more popular is also the simplest: the later forms evolved directly from the earlier ones. However, an alternative, first proposed in 2015, keeps the idea that the ancient and Tiberian hippos are distinct species. Under this proposal, the "real" H. antiquus evolved directly from the oldest known species of the genus, H. kaisensis, from the African Rift Valley. It then died out 1.7 million years ago to be replaced by a new species that evolved from H. gorgops. If this is true, then the Tiberian hippo would either have to be restored as a species or described as a variant form of its African relative; either way, we would have three hippo species in Ice Age mainland Europe, not two.

One interesting feature of this newly described jawbone, however, is how small the canine tusks are. They are distinct and prominent, as we would expect of a modern hippo, but quite a bit smaller. While this same feature has been noted in some other fossils of the same age (including at least one from Germany), in many others, the tusks are enormous, larger than those of the modern animal. The most likely explanation for this is that the Italian fossil belongs to a female.

Male hippos today have larger tusks than females, although that's at least partially because they are larger overall. This new analysis suggests that the same must have been true of the "Tiberian" hippo too, but to a much greater extent, so that it would surely have been obvious in life. This is far less true of the early forms of the ancient hippo, suggesting a change that became exaggerated as it evolved.

The teeth of an animal can also provide us with information about its diet. The general shape of the teeth is much the same in all of the Hippopotamus species, or they wouldn't be assigned to the same genus in the first place. But a closer look can show the presence of microscopic scratches and pitting that can give us more detail about things such as food toughness, while analysis of isotope ratios can also separate some food types from others.

The modern hippopotamus eats mainly grass, an abrasive foodstuff that leaves distinctive scratches on the tooth surface. In contrast, the ancient hippopotamus has a different pattern that suggests softer food, which, together with isotope and other evidence, is thought most likely to indicate lush water plants, soft leaves, and fruit. This may also explain the narrower snout, since grazing animals tend to have wider mouths to shovel more food in, rather than picking out the best bits or focusing on particular plants.

The new study shows a shift here, too, with the later "Tiberian" hippos lying somewhere between the older ancient hippos and the modern species. H. antiquus, it seems, may originally have evolved to be even more aquatic than the living species, not bothering to graze much beyond the riverbank, but it shifted towards a diet closer to the modern species with time.

Perhaps it didn't have much choice, as the Ice Ages changed the flora of Europe even beyond the tundra zone, where ice-covered rivers would have presented a more intractable obstacle. At the time the Tiberian hippo was alive, central Italy had a relatively dry, cool, climate, with an open landscape. The dominant vegetation consisted of plants like sagebrush and heather, which might have forced water-dwelling hippos to consume a wider diet than they had previously. Indeed, the fossil analysed in the study had unusually thin enamel, which might indicate that the animal in question had struggled to find enough nutritious food to keep itself fit through the winter.

All of this indicates that, even if the minority theory about the Tiberian hippo having evolved separately from its earlier counterparts is wrong, the ancient hippo changed over the million-plus years of its history, probably in response to the worsening climate. The authors point out that, if we find more complete remains of the animal, there may be enough differences in the bits we haven't seen yet to restore it to its former status as a distinct species. That's pure speculation on their part, of course, since we don't know what we don't know.

But could what we have already found be enough to designate it as an identifiable subspecies? Well, that, at least, is a plausible proposal.

[Photo by "FunkMonk" from Wikimedia Commons. Cladogram adapted from Pandolfi et al. 2020.]

All the World's Antelopes: Sables and Other Horse-Antelopes

2026-08-23T17:10:16.983+01:00

Sable antelope (male)

The hippotragines are one of several small subfamilies of antelope. Small that is, in terms of number of species, because physically they are quite large. The name literally translates as "horse-goat", but that second part is often used taxonomically as a term for antelopes, so "horse-antelope" might be closer to the intent. It was coined in 1845, partly on account of the physical build of the animals, with their long legs and muscular, horse-like necks.

The subfamily includes the oryxes and gemsbok, but arguably the most horse-like members of the group are the sable antelope (Hippotragus niger) and its closest relatives. Sable antelopes stand around 140 cm (4'7") at the withers, which is almost exactly the official height that separates full-size horses from ponies. They weigh between 160 kg and 230 kg (350 and 510 lbs), which is well within the range for domesticated ponies, indicating a slighter build than animals bred, in part, to bear the weight of humans. Their shape, however, is quite horse-like, an effect accentuated by the presence of a clear mane down the back of the neck.

The name comes from the colour of the adult males, which is jet black over most of the body, with clearly offset white underparts and rump. The chin and the sides of the face are also white, with a narrow black stripe running down the middle of the cheeks. Females, and males under three years of age, are instead a dark chestnut, but maintain the same white markings. The horns are long and curved into an almost scimitar-like shape, with numerous rings along their length. They reach as much as 165 cm (65 inches) in the largest males, but are about a third shorter in the females.

Sable antelopes live in southeastern Africa, from the southern tip of Kenya to northern South Africa. Four subspecies are currently recognised, with the most northerly sometimes being considered a distinct species; they vary in details of average size, the colour shade of the females, and the exact shape of the facial markings. Among these is the "giant sable antelope" of Angola, which is slightly larger than the others, with larger horns. Genetic studies have revealed that this diverged from the other subspecies around 170,000 years ago, during the second-to-last Ice Age. While sable antelopes as a whole are reasonably common, partly due to about 25% of them being kept on private land, the giant species is almost extinct, with fewer than a hundred adults thought to be alive and subject to near-constant poaching.

They inhabit open savannah woodlands dominated by miombo (a leguminous tree common across much of southern Africa). Highly dependent on open water, they stick to river valleys and lusher grasslands during the dry season, but they move onto higher slopes during the wet season, where greater tree cover can afford them better protection. They tend to avoid the most open of plains, but anywhere with good grass growth will do in a pinch.

Studies of their diet indicate that they eat almost nothing but grass, although they are surprisingly picky about the grasses they prefer, with one study showing that 90% of their diet consists of just four species. In addition to panicgrass, red grass, and speargrass, this included a species of Chrysopogon that, while relatively common, is avoided by zebras and other local antelopes, allowing them to live alongside one another without competition. They also frequent salt licks, and have been known to chew on dry bones for their mineral content.

Sable antelope are most active in the morning and early afternoon, resting during the hottest parts of the day. Females live in herds of between 15 and 25 individuals, led by the oldest member, at least until she becomes physically unfit. The dominance hierarchy within the herd is unusually strict and long-lasting, with females often fighting with one another, especially when they are ready to mate, and being highly aggressive towards any other female they consider an intruder. The herds themselves are also mutually hostile, although they will gather together in larger groups in places where the grass is especially lush and they can feed without having to battle for resources.

Adult males, in contrast, mostly travel alone, each maintaining a territory of 25 to 40 hectares (65 to 100 acres), far smaller than the wide ranges over which the females travel of 25 km² (10 square miles) or more. Nonetheless, males will attempt to keep passing females within their territory for as long as they can manage; their success rate at this is apparently widely variable, with some keeping almost constant contact with at least one herd, and others barely getting a look-in. While they generally drive away any rival males from their territory, they are more tolerant of low-status individuals who show no interest in mating.

Males mark their territory by dropping dung and regularly patrol it on the lookout for potential rivals, thrashing vegetation with their horns as they go. Nonetheless, invitations to sparring bouts are surprisingly civil, with the bull approaching his target with his head held at shoulder level, and then gently nudging him with his horns until he gets a response. A male holding his head down and tucking his tail in is a sign of submission, typically used by younger males towards a dominant bull.

There is no strict breeding season, although births are more common between January and March, in the middle of the wet season. The system is essentially one of harem breeding, and results in the birth of a single calf about eight months later. Births among higher-ranking (older) females tend to occur around the same time, apparently synchronised through scent marks in their urine.

After birth, as with most antelopes, the mother hides her infant in long grass or similar cover. They remain there for about the first three weeks of life, before slowly integrating with the herd over the next three weeks. The synchronised births allow the calves to remain close together in crèches while they are hiding, and to join the herd together once they are collectively old enough to do so. While they are hiding, the mother remains close by, but not so close as to give away the location of her calf, calling to it only when she fails to see it where she expected... mothers are apparently not so good at remembering exactly where they put their calves as one might think.

Young calves play with their peers, not distinguishing between them based on their sex, presumably as a means of honing their skills and assessing their development. They become sexually mature at about two years, long before they are fully grown or, in the case of males, have their black coat. Females stay with the herd, but males move out around the time of sexual maturity, forming their own small bachelor herds of 2 to 12 individuals. These eventually break up when they reach full physical maturity at around five or six years of age.

Roan antelope

The roan antelope (Hippotragus equinus) once lived across almost the entirety of Africa's savannah zones, north, east, and south of the central jungles, from Senegal, round through Kenya and Uganda to Angola and South Africa. It's no longer quite so widespread, having been eliminated in much of its range, especially in the east, where it has (for example) vanished altogether in Burundi. Nonetheless, it remains a common animal, with no fewer than six subspecies being recognised across its wide range.

In many respects, it is remarkably similar to its close relative. It is about the same size and build as a sable antelope and, like it, has a horse-like mane on its neck. However, the males are not black, and while the name might suggest a mostly dark colour interspersed with white hairs, there is considerable variation between individuals, with some being remarkably pale. There are nonetheless black markings on the face, which are more extensive than on the sable antelope.

They inhabit savannah woodlands, preferring areas with long grass but a reasonable amount of tree cover, both of which also tend to correlate with the amount of available drinking water. Depending exactly where they live, their diet has been recorded to consist of anything from 90 to 100% grass, although we do not have the fine detail that we have with the sable, so it is unclear exactly how similar their diets are.

Their patterns of social behaviour are also similar, although males seem more inclined to follow the herds about, taking the lead from the oldest female, so long as they can exclude other males from joining them. More commonly, however, they are territorial as the sables are, although they apparently do not scrape the ground with their hooves before leaving droppings, as their relatives do. As one might expect, those in drier areas with less abundant grass tend to range over wider areas than those around river deltas and the like.

One of the few studies conducted on their reproductive habits suggested that female drop to their knees to indicate a lack of interest in mating. Otherwise, the process is much the same, with the males maintaining a harem. Females remain receptive for up to three days, during which time, they have occasionally been seen to engage in lesbian sex, although it's hard to know exactly what that means in a non-human species.

Addax

The closest living relative of the sable and roan antelopes is the addax (Addax nasomaculatus), once found wild across the southern edge of the Sahara, from the Atlantic to the Nile. Now, however, it is virtually extinct, with the only definitively known population inhabiting one small region in central Niger. That population is thought to include fewer than 100 adults, meaning that it is unlikely to be viable in the long term. Reports occasionally come in of sightings elsewhere, notably Chad and Mauritania, but assuming these are accurate, the populations there must be so small that local extinction would be unavoidable.

Fortunately, this excludes those addax living in captivity, of which there are at least 600 in formal breeding programs, and possibly twice that many unrecorded on private ranches in the US. Attempts to reintroduce them to the wild have already begun, although none have yet reached the level to be considered a success. But, while the animal is listed as critically endangered, it's thought that its chances of surviving (although not necessarily flourishing) are actually quite good, with its current tiny population almost certain to increase over the next few decades.

Addax are smaller than sable and roan antelopes, standing around 110 cm (3' 7") at the shoulder, and with even the largest males weighing no more than around 100 kg (220 lbs). They have a pale grey coat, that fades to near white on the underparts, although are black patterns on the face and a small bald patch behind the nostrils. Their most notable feature, however, is their horns, which are present in both sexes, and twist in a wide spiral three or four times along their length.

Perhaps the most desert-adapted of all antelopes, they inhabit some of the most desolate regions on Earth, even venturing into the sand fields while travelling between grazing grounds. Their wide-splayed hooves help with this, giving them purchase even on soft ground. While they mainly eat grass, that's because there is little else where they live, and they will happily consume bushes and shrubs if they come across any. Analysis of their digestive tracts has shown that they retain food in their guts for longer than most other ruminants, partly as a consequence of the slow-fermenting grass that they eat, and partly to absorb as much moisture as they possibly can; addaxes do not need to drink, although they will if they can.

Herds, as inferred largely from captive animals, are small, with between 5 and 20 individuals. They are highly nomadic, roving widely across the desert in search of patches of edible food or following the infrequent rains. During storms and cold nights, they shelter by digging hollows in the sand and hunkering down to wait out the weather. The herds seem to have the same structure as in sable antelopes, with a dominant female leading the way, and a structured hierarchy beneath her. Less is known about how the males behave in the wild, where they can range as they will, but they establish territories when kept in captivity and try to guard harems from rivals.

The single calf is most commonly born in the winter or spring, and spends the first few days of its life hiding in the minimal shelter available. They rejoin the herd more quickly than sable antelope do, at around two weeks of age, living in crèches with others of the same age from then on.

Bluebuck

There was, however, one other species of hippotragine antelope in recent times. This was the bluebuck (Hippotragus leucophaeus), a close relative of the sable and roan antelopes and generally similar to them in form. It was distinguishable by a slightly smaller size, similar to an addax, and a bluish-grey coat without any of the facial markings seen in the other species. It used to live in South Africa, on the coastal renosterveld, a grassy habitat close to the Cape. At the time, this was grassier than it is now, but the arrival of white colonists eliminated most of the large local herbivores, changing the floral composition of the landscape.

The bluebuck was the first hippotragine species to be scientifically described, in 1766, but it was also the first species of large African mammal to go extinct in historical times. The last individual is thought to have been shot in 1800, a remarkably short time after its discovery, probably due to the population already being small and restricted to a small area when Europeans first arrived. Today, a few specimens remain in museums, although many labelled as such have turned out to be sable or roan.

Given how long ago this was, and how briefly the living animal was known to European naturalists, we know very little of what these animals would have been like, barring their physical appearance. We can assume a similar grass-based diet to their close relatives, based partly on their obvious similarity, and partly on where they are known to have lived. A 2013 study based on skeletal remains going back thousands of years suggested that they were migratory, calving in the winter at the west of their original range, when grass was at its lushest, and then heading east following the summer rains before returning in autumn. Changes in the climate after the end of the Ice Ages rendered this tactic less effective, reducing their population until white colonists delivered the final blow in the 18th century.

Although it was long thought otherwise, genetic studies on the few available remains have shown that the bluebuck was more closely related to the sable than to the roan antelope.

While we know of some fossil species, that brings me to the end of the recent species of "horse-antelope". Next time, I will be taking a first look at another, similarly small, subfamily of antelopes, ones that live in much damper habitats...

[Photos by Bernard DuPont, Charles J. Sharp, and Zachi Evenor, from Wikimedia Commons. Drawing by Joseph Wolf, in the public domain. Cladogram adapted from Bibi, 2013.]

Otter Whiskers

2026-08-16T15:29:32.297+01:00

Four years ago, I posted about whiskers, a feature common to the majority of mammal species, from horses to mice. They are so widespread that they must have evolved very early on, probably well before marsupials diverged from the placental mammals, back in the time of the non-avian dinosaurs. Even so, as humans, we are probably most familiar with them from domesticated animals, especially the carnivorous ones that so often share our homes.

The carnivorans form a natural evolutionary group within the placental mammals, arbitrarily (if conveniently) ranked as an "order". The various living families within this order can in turn be classified as either "feliform" or "caniform", depending on whether they are more closely related to cats or dogs. The dog-like group contains a great many species, which might be more varied than we would think at first glance.

Tracing back the family tree of the dog-like carnivores, ignoring various extinct groups, we can see that the first family to split off from the others was that of the dogs themselves, with the bears coming next. The third split, however, saw one group of dog-like animals entering the water and becoming highly adapted to that environment. These are the seals, sea lions, and walruses, with the remaining group of dog-like carnivores being collectively referred to as "musteloids", and including skunks, raccoons, and the highly diverse weasel family, which itself incorporates everything from badgers and stoats to otters.

Like all other dog-like carnivores, seals and their relatives have whiskers. In fact, they have what are probably the most sensitive and highly specialised whiskers of any mammal. (Although, to be fair, there hasn't been extensive research on the matter, so it's hard to be sure.) In fact, the whiskers of seals have, collectively, ten times as many nerve endings as those of, say, polecats. Compared with their land-dwelling relatives, their whiskers are also shorter, thicker, and stiffer, with a smoother surface.

This is unsurprising, because the primary purpose of whiskers is to sense the environment through a highly developed sense of touch. It may be the most important tactile sense for many species, and that is going to be especially so for those animals that move around in dark spaces. That includes nocturnal animals, of course, as well as those that spend their lives in burrows and tunnels, but moving along the bottom in deep water also counts. The fact that water is more resistant to motion than air probably explains the enhanced stiffness of aquatic whiskers.

Indeed, the whiskers of seals have probably been studied more closely than those of any animal other than rats and mice. But if the unusual sensitivity and shape of their whiskers are an adaptation to their aquatic habits, we should see something similar in semi-aquatic mammals. This has, in fact, been checked, with some studies comparing seals and land-dwelling musteloids with their semi-aquatic kin, the otters and mink.

These have generally found that the whiskers are, as we might expect, often intermediate between those of related aquatic or terrestrial animals. By some definitions, seals themselves are semi-aquatic, since they often sleep on land and spend most of their time there during the breeding season and when they are very young. But here, we are using the term in a more typical sense that excludes seals but would include animals that spend a lot of time swimming for food, but are also agile on land, often sleeping in burrows or the like. Outside of the carnivorans, muskrats and hippos would fit this description and, further afield, we could include penguins and crocodiles.

However, it is only in the last few months that a dedicated analysis of otter whiskers and their use has been published. So let's take a look at what it uncovered.

We should start off by saying that there are at least thirteen recognised species of otter, with a fourteenth having recently been added to one of the most influential lists of such things. Of these, one, the sea otter (Enhydra lutris), is, under the definition used above, fully aquatic, since while it can move about on land, it doesn't really have to. The others are all decidedly semi-aquatic, forming a distinct branch within the weasel family, thus being comparatively close relatives of the seals, but the product of a distinct, later, evolutionary event.

In this case, the study looked at one particular species: the common or Eurasian otter (Lutra lutra). The researchers were able to acquire five deceased otters from the National Museum of Scotland for anatomical examination, and a live one from the Wildwood Trust in Kent, to analyse its behaviour.

The first thing to note is that, as with many mammals, otter whiskers are not restricted to the area we immediately think of, to either side of the snout. In addition, there are smaller clusters of whiskers above the eyes, on two patches on either cheek, and below the chin. These are, as they are in cats, smaller and finer than the primary or "mystacial" whiskers, but are doubtless just as important in giving the otter a complete tactile sense of its immediate environment.

The mystacial whiskers are, as in all mammals studied so far, arranged in a regular grid pattern. In this case, they are arranged into seven rows of eight, with the whiskers getting progressively smaller and more closely packed towards the snout, where an irregular set of tiny whiskers lies in front of the true mystacial ones. The exact pattern seems to vary between individuals, and may well be unique, in the same manner as human fingerprints. This is known to be the case for cats, including lions, although the researchers concede that it would probably be of little practical use for identifying individuals.

The whiskers themselves are, as indicated in previous studies, thicker and stiffer than those of land-dwelling animals, such as foxes, but not quite so much as in seals. However, seal whiskers are unusual in having an oval cross-section, rather than a round one, which may help them move through the water; otters, it turns out, do not.

Most mammals move their whiskers in a cyclical motion like... well, a whisk. The observations of the live animals in this study, however, showed that, like seals, otters do not. This is probably because of the greater resistance provided by water than air, which might make such motions tiring for the animal. Instead, they push their whiskers forward and back, aided by stronger and more organised muscles beneath the skin of the snout.

These muscles form regular strips between the whisker rows, running the full length of the mystacial pad that bulks up the tissue beneath them. This is not what we see in, for example, rats, but it is very similar to the pattern in seals, suggesting its role in their particular whisker motions. Like most other mammals, including rabbits and hedgehogs, otters can twitch each side of their nose independently, pushing the whiskers of one side or the other forward to get a better feel for the environment.

One test that the researchers gave to their otter involved what they describe as a "texture discrimination enrichment device". This is basically a framed plastic sheet with six small doors in it. The doors are either smooth, finely ridged, or comparatively rough, with food being hidden behind only the roughest of the doors. The otter's task was to quickly learn where the food was hidden and identify the right doors using its whiskers alone.

When presented with this task, the otter used its whiskers in the same way, and at about the same speed, as seals and sea lions had previously managed in similar tests. In fact, once it had learned the trick, it could identify the correct doors more quickly, being able to tell the difference in 0.2 seconds instead of 0.5 seconds. For comparison, it takes a human using their fingertips about 5 seconds to detect the same difference, giving some idea of the sensitivity of whiskers, at least on this particular type of task.

This inevitably leaves some questions unanswered. Perhaps most importantly, we don't know how widely these principles hold. The authors suggest extending the study to other otter species that are relatively easy to obtain from zoos, such as the Asian small-clawed otter, as well as seeing whether there are differences in the fully aquatic sea otter. But it strikes me that it would be interesting to know how other semi-aquatic animals have developed their whiskers. We know a lot about the whiskers of rats and mice, but how do those compare with beavers?

It's a small feature of animal anatomy, but one that is very important for the animals themselves and for how they navigate and interpret the world around them.

[Photo by Claudia Peters, from Wikimedia Commons.]

Eocene (Pt 5): Cerberus and the Pangolins

2026-08-09T16:31:28.247+01:00

Eurotamandua

Today, when we think of large carnivorous land mammals, we think of such things as dogs, cats, and bears, but, while some of these families do date back to the Eocene, they were not found in Europe at the time. Instead, the dominant group of carnivorous mammals were the hyaenodonts.

While the name translates as "hyena-tooth" due to the description of the first fossils to be found, hyaenodonts were not hyenas, or even closely related to them. They belonged to a group entirely separate from the living carnivorans, and that survived alongside them until as recently as 10 million years ago, near the end of the Miocene. For most of that time, they could be regarded as primitive holdovers, vestiges of their past glory, but in the Eocene they were still at the height of their power.

Having said this, the first hynaenodonts to enter Europe were physically unimpressive, succeeding largely due to the fact that there wasn't much else to compete with. These are traditionally grouped into a subfamily called the "proviverrines", although the details are debated. For one thing, it's not at all clear which family (if any) they are a subfamily of. This is largely due to the higher-level classification having shifted since they were first named, but the membership of the group is also in doubt, since it's not at all clear that all of the traditionally defined species share a unique common ancestor with one another.

One animal that we definitely can say is proviverrine is Proviverra itself. This was about the size of a small stoat, at around 20 cm (8 inches) in length. While they had longer legs, if not particularly suited for fast running, they probably ate much the same diet as stoats, too, feeding on small mammals and birds, and likely some insects. While its teeth were only just developing the meat-cutting blades that would later become common in hyaenodonts, analysis of the inside of the skull suggests a brain that was relatively large for its size, comparing favourably with many modern carnivores.

While the proviverrines are usually regarded as being unique to Europe, they prospered there, with several different species having been described. As time went on, they became larger and more specialised. Arfia, for example, although now often placed in a separate subfamily, was about the size of a fox, and had limbs adapted for chasing down prey, albeit with enough flexibility that it may have been able to climb trees if it wanted to. On the other hand, Lesmesodon, one of the smaller species at no more than 400g (14 oz.), had teeth that seem particularly well suited to eating insects, while Eurotherium, weighing in at up to 5 kg (11 lb.), would likely have eaten much more meat and may well have been a scavenger.

If they are separate groups, one theory holds that proviverrines proper originated in Africa, while animals such as Arfia came across from North America. They would have done so, not by crossing a land bridge across the Bering Strait, as was more common in later geological times, but across the North Atlantic. This is because the most northerly reaches of the Atlantic Ocean were closed off at times, making it possible to walk from Canada, via Greenland, to Norway and Scotland.

It is possible that Hyaenodon itself, which first appeared in Europe during the Middle Eocene around 41 million years ago, followed this route, since it originated in North America much earlier... but it is perhaps more likely that it came the long way around, through Asia. Although better known from its larger, American forms, the European ones were relatively small, with some estimated as weighing just 2 kg (4½ lbs.), smaller than most domestic cats.

This is not to say that larger mammalian carnivores did not inhabit Europe, at least by the Middle Eocene. These belonged to a group of hyaenodonts named the hyainailiourines, which may have originated in either Asia or Africa.

Pterodon was only the second hyaenodont of any kind to be described, back in 1839. Although that early description includes some limb bones, they have since been lost, and it isn't clear that they really belonged to the same animal, so all we have for certain is the skull. Based on this, it has been estimated it may have weighed around 30 kg (66 lbs.), similar to a retriever or English setter. Inevitably, however, there is a lot of uncertainty in that, given that we don't know the exact shape of its body. However, since we do have the teeth, it was clearly a flesh-eater and may have had some limited ability to crack bone.

The largest known mammalian carnivore in Eocene Europe was Kerberos, named for the three-headed dog guarding the Greek underworld. First described in 2015, the only known fossil came from the Tarn region of southern France. That study estimated the animal to have weighed up to 140 kg (310 lbs.) in life, similar to an adult lioness. Because, unlike Pterodon, we do have one of its legs, we can say that it had flat feet, similar to those of a bear, and so would have walked along the ground. The general shape, however, suggests that it would not have been a pursuit predator, and probably wasn't very good at climbing, either. It was clearly highly carnivorous, and would have scavenged on carrion when it was available, with the teeth and jaw muscles likely strong enough to crack bone, but not ideally suited to doing so.

It wasn't quite the top predator of its day, since Europe, like many parts of the Eocene world, was also home to gigantic crocodiles, but it must have been close.

During the Early Eocene, however, before Kerberos lived, it's unlikely that the largest mammalian carnivore would have been a proviverrine, or even a hyaenodont. At least two groups of relatively large carnivorous mammals did exist, although each was represented by relatively few species. Palaeonictis somewhat resembled a wolverine in borth size and shape, and is better known from North America, where even larger forms lived. Given the heavy build that this implies, it probably wasn't a fast runner, although some of its features suggest that it may have been able to climb trees. It was an oxyaenid, a primarily American group related to, but distinct from the hyaenodonts. They died out in Europe at the end of the Early Eocene, perhaps only living there for a few million years.

The mesonychids were less closely related to the creodonts, being thought to be closer to the hoofed mammals. Despite this, they were carnivorous, and while they, too, were predominantly American, they briefly entered Europe in the Early Eocene. Two examples are known; Pachyaena, a roughly wolf-sized animal living on the northern islands of the archipelago, and the badger-sized Hyaenodictis in the south. The latter lasted longer, dying out 48 million years ago, as the Middle Eocene dawned, although whether it was out-competed by the proviverrines or became extinct for some other reason is not obvious.

There were probably no true carnivorans in Eocene Europe, in the sense of anything descended from the last common ancestor of the living forms. However, a broader definition could include anything closer to the carnivorans than to the hyaenodonts and oxyaenids and there were some animals on the continent at the time that fit that description at least.

Perhaps the closest such animal in Europe to the living forms was Quercygale. This was first described from the Quercy Phosphorites, a major Cenozoic fossil formation in southern France, but is also known from Germany, Switzerland, Spain, and the Isle of Wight in England. It was about the size of a house cat, although with some variation among the individual species, and, if it was anything like some of its other relatives, was probably arboreal. It was also unusually successful, surviving for almost the entire length of the Eocene - hardly a short span of time. Analysis of the inside of the skull suggests a brain smaller than would be expected of a modern carnivoran of the same size, with less developed cerebral cortices, but not necessarily by much.

Other carnivorous mammals were even less related to the modern animals than were the hyaenodonts. Anatoliadelphys is an extreme example, a metatherian carnivore that survived into the Middle Eocene in Turkey (then the easternmost major island of the European archipelago). Related to today's marsupials rather than to placental mammals, it must have been a late survivor of some ancient lineage that we otherwise know little of. It had strong jaws and large teeth suited for biting down on hard objects, and was likely adept at clambering about in the trees, using what appears to have been a prehensile tail for support.

If the mesonychians were related to the herbivorous hoofed mammals, but were themselves carnivorous, the opposite seems to have been true of the pantolestans. They, so far as we can tell, belong to the same section of the mammalian family tree as the carnivorans, but their teeth suggest that they ate plants. Europe was home to one particular family within this group, the paroxyclaenids, which were tree-dwelling fruit-eaters. While most, such as Merialus and Paraspaniella, were much smaller, the largest, Welcommoides, reached 4 kg (9 lbs.), the size of a large cat, and successfully crossed the water to Asia, reaching as far as Pakistan. Most died out around 48 million years ago, at the end of the Early Eocene, but a few managed to survive for a further 10 million years, perhaps eventually wiped out by the unusual heat of the Eocene Climatic Optimum at around that time.

However, one other group of carnivoran relatives was much luckier. They may have diverged from the common ancestor of carnivorans, hyaenodonts, oxyaenids, and all those difficult-to-classify "stem" carnivoramorphs such as Quercygale, at about the same time as the pantolestans did. Which is to say, very early on, perhaps around the time of the extinction of the non-avian dinosaurs. But not only did they survive into the Eocene, they are still alive today.

These are the pangolins. The oldest known pangolin is Eomanis, which is known from Germany, very far from where pangolins live today. It was remarkably similar to the modern animals in size and shape, and, while the details of anatomy diverge just enough to place it in a different family than that we have today, they are close enough that it is difficult to see what else it might be. The well-preserved fossils reveal that the scales did not extend onto the tail, and that it still ate some fruit, which the modern species generally do not.

If that was a surprising animal to find in Germany, Eurotamandua was even more so. When it was discovered in 1981, it gave every impression of being an anteater, and was classified as such. In retrospect, this made no sense, as anteaters are unique to South America, and it's very difficult to see how any could have reached Germany from there. Later examination of the skeleton determined that it lacked many of the defining features of true anteaters, and it was instead placed with the pangolins.

Nonetheless, the well-preserved fossil indicated that it was not scaled, but was instead furry, as we would expect an anteater to be. The assumption at the time was that it represented an early branch that had split off before the scales had developed. A new analysis, conducted in 2023 but only formally published in May of this year, places it a little further away - closer to pangolins than to anything else alive today, but outside even the order, let alone the family, of the modern species.

[Photo from Rose et al. 2026, available under CC-BY-4.0.]

All the World's Antelopes: Gemsbok and Oryx

2026-08-01T18:05:09.727+01:00

Gemsbok

As I have discussed previously, there is no such thing as an antelope, in the strict scientific sense. That is to say, they do not form a natural group of organisms, being defined only as those members of the cattle family that aren't sheep, goats, or obviously cow-like. This covers a wide range of animals, some closely related, but others much less so.

I've previously looked at the various species of gazelle, and at the spiral-horned antelopes (which are actually "bovines"). Now it's time to look at the others.

Linnaeus' original catalogue of scientific names, published in 1758, included five species that we would now call antelopes. In that catalogue, they are listed as goats, based primarily on the shape of their horns, and therefore sit alongside the chamois and ibex. Two of these, the dorcas gazelle and the blackbuck, are now placed within the gazelle subfamily, while two others are relatively small "dwarf antelopes", which I will cover later.

The other is the gemsbok (Oryx gazella), which, despite the name that Linnaeus chose for it, is absolutely not a gazelle. He described it as living in India, which was either a mistake on his part or a staggeringly broad definition of "India", given that it actually inhabits southwestern Africa. More specifically, they are found in the wild across Namibia, most of Botswana, and the northern and western parts of South Africa. They may cross the border into Zimbabwe, and are certainly found in game reserves there, but no longer cross the Kunene River into Angola as they once did.

They were also introduced to New Mexico in the 1960s as game animals, apparently to replace native pronghorns strafed by the USAF during training missions in the 1940s. Discovering a complete absence of lions, leopards, and hyenas, the gemsbok prospered to the point that they may now pose a threat to the native ecosystem, with cougars apparently unable to take up the slack.

Their native range is, you will note, a particularly desolate and arid part of the world, with much of it lying inside the Kalahari Desert. Indeed, gemsbok are very much creatures of the open plains, inhabiting wastelands too barren for most other animals of their size. They will enter sparse savannah woodlands when they have to, but only to cross between open spaces, perhaps fearful of what predators might be hiding there.

The word "gemsbok" comes, via Afrikaans, from a Dutch word meaning "chamois-buck", but it's hard to see why, given that they do not look even remotely like a chamois. They are, instead, moderately size antelopes, standing around 120 cm (4 feet) high at the shoulder, with both sexes having long, straight horns that can reach as much as 150 cm (4' 11") in length. They are a pale sandy colour over most of their bodies, but with a black stripe down the middle of their back and wide black stripes along the flanks. The face is white, with clear black markings, and there is a short, dark mane running down the neck. Males are slightly larger than females, but not by as much as in some other ruminants.

As one might expect, gemsbok have several adaptations that help them survive in their arid environment. Some of these are behavioural; they are most active during the cooler parts of the day and, while not truly nocturnal, also during moonlit nights. Understandably, they will seek out shade when they can find it and, when they can't (as is quite common where they live), position themselves so that the smallest part of their body is facing directly into the sun. They can also raise their body temperature by a full 4°C (7°F) during the hottest parts of the day so that they sweat less than they otherwise might.

They can go without water for protracted periods, and probably don't inhabit lands further east because the winters become uncomfortably wet; attempts by ranchers to introduce them to these areas have generally not been successful. An annual rainfall of about 30 cm (12 inches) seems to be the upper limit that they can tolerate, and even when they could forage in areas with damp soils caused by water drainage, they avoid doing so, sticking to rocky hillsides and dunes with short grasses.

They mainly eat grass, especially during the wet season when fresh sprouts appear. During the dry season, their diet becomes somewhat broader, so that they sometimes feed on shrubs and trees, and regularly dig into the soil to get at roots, bulbs, and wild cucumbers, sometimes reaching as deep as 1 metre (3 feet).

They live in small, mixed-sex herds of 5 to 40 individuals. These tend to remain in small, probably territorial regions, travelling no more than 2 km (1¼ miles) a day, unless they are spooked by a predator. Some older males, however, live on their own, keeping apart from their fellows, but able to visit multiple herds. While they can survive for days without water, they drink heavily at waterholes when they can, queuing up to do so, with the larger males pushing out everyone else to drink first - to the extent that females and young are first to die off during times of drought.

There does not seem to be a specific breeding season, with mating occurring throughout the year. Both the solitary males and those travelling with the herds get a look in, although the full details of their dominance hierarchies are not known. Newborn young are hidden in thickets, one of the few times that gemsbok will give up the advantage of open terrain with a clear view of their surroundings. They leave to rejoin the herd at three to four weeks of age, by which time their horns have sprouted. All the lactating females in a herd feed their young at the same time of day, after having rested.

The gemsbok is a relatively common animal and, partly due to ranching reducing the demand for trophy hunting and partly due to them living where nobody really wants to go, their population is thought to be stable, and likely well over 350,000. The same cannot be said for their closest relatives.

Arabian oryx

The Arabian oryx (Oryx leucoryx) is one of the headline success stories of conservation, to the point that the premier journal of conservation science is named after it. In many respects, they are similar to gemsbok, although with just a 90 cm (3 feet) shoulder height, they are considerably smaller. They are also much paler in colour, almost white over most of the body, with dark brown on the legs, fainter markings on the flanks, and less black on the face. The horns are narrower too, with fewer rings, although they can still be remarkably long.

It is native to the whole of the Arabian region and to the desert regions to the north, once being found from the Sinai in Egypt across to Syria and Iraq, and as far south in the Arabian Peninsula as one could go. Perhaps even more than the gemsbok, it prefers desolate desert regions, living amongst sand dunes and bare rocky plains. They can happily tolerate daytime temperatures of up to 45°C (113°F) and, while they will drink when they can, appear able to survive indefinitely without water beyond that in their food, being unaffected by droughts lasting as long as six months.

By some measures, they are more drought-resistant than a camel.

Quite how they achieve this is unclear, although we do know that they retain more water than camels do in hot and dry conditions, being able to adjust their body temperature upwards by over 7°C (13°F) to reduce sweating. Like the gemsbok, they are active only during the day in winter, but around dawn and dusk, and well into the night during the hot days of summer. In fact, they only sleep around half as much in summer as in winter, averaging 3.7 hours per day, which they do during the day, instead of at night as they do in winter. They also have adaptations that allow them to keep their brain cooler, relative to their general body temperature, than other animals (including gemsbok), likely reducing the risk of heat stroke.

They eat much the same food as gemsbok, but perhaps with an even heavier emphasis on grass. Their herds are smaller, with around ten individuals each, and are highly mobile, wandering across vast stretches of desert. There is no set pattern to these migrations, which are driven partly by their apparent ability to sense rainfall at a distance and head in the direction of the resulting plant growth. The ranges of herds overlap, without apparent territoriality.

Even within the herd, the animals travel spaced out, with females without young at the front, followed by those with infants, then the dominant males, with subordinates bringing up the rear. Each adult grazes about 5 to 10 metres (16 to 33 feet) apart from the others, making the best use of sparse resources while still ensuring that the rest of the herd is clearly visible. Dominance is established by posing and looking tough rather than by actually fighting; so far as possible, they use their horns only in defence.

Breeding, and the way they raise their young, is much the same as in the gemsbok, with no set mating season. Males are, however, less inclined to travel on their own after reaching adulthood, although it does happen.

But perhaps one of the most remarkable features of the Arabian oryx is that it exists at all. Numbers were rapidly declining due to hunting to the point that they had almost vanished by 1960. In 1962, the Fauna and Flora Preservation Society of London hatched a plan to save them from what seemed certain doom. They had originally planned to move a herd to Kenya, where they could be watched and protected, but that didn't work out, so they moved them to Phoenix Zoo in Arizona instead, initating a captive breeding program. In 1968, the Sultan of Abu Dhabi founded his own zoo partly for the same purpose.

The projects were successful, allowing the captive animals to breed and produce young. Just in time, too, since it is now thought that the last wild animal died around 1972.

Sometimes, such projects prove unable to restore any of the animals to the wild, but not so here. Reintroductions to the wild began in 1978 in Jordan and have continued since, with descendants of the original herd being shipped to many other zoos to maintain the program. The Jordan program itself failed, being suspended in 1997 due to pressures caused by an influx of refugees from the Gulf War in Kuwait, but others continued.

Today, the largest number of wild Arabian oryxes live in Saudi Arabia, followed by the UAE (although it's debated how truly "wild" some of these latter are), with smaller populations in Oman and Israel. There are even some in Jordan, with the project having restarted in 2014. The total wild population is thought to be over a thousand, and seems to be stable, retaining more genetic diversity than might be feared given their near-extinction just over 40 years ago. This population, it should be noted, is high enough that the animal is no longer officially listed as an endangered species by the IUCN, although it certainly qualifies as threatened.

Moving south again, we come to the beisa oryx (Oryx beisa). The status of this species has been debated down the years, with it being considered a subspecies of the gemsbok for much of the 20th century. However, after being raised to species status in 1997, it was proposed in 2011 that it be further split into no fewer than three species. While these new species were recognised in some publications, they are generally considered as one today, albeit divided into two subspecies. (The third proposed species apparently interbreeding too much with one of the others to receive even that much distinction).

Beisa oryx
(southern "fringe-eared" subspecies)

Taken as a single species, beisa oryx live across eastern Africa from central Ethiopia to northern Tanzania. They are similar in size to the gemsbok, and have a similar coat pattern too, albeit with much narrower black stripes on the flanks and back, with the latter only covering the rump, fading away further forward. The southern subspecies had distinctive black tufts on its ears, one of the grounds for considering it to be a separate species back in the day; further genetic analysis may yet resurrect this status.

It is less desert-adapted than its kin, as one might expect given the climate in this part of Africa. Instead, its habitat can best be described as semi-arid grasslands and scrub, dry by the standards of many places, but not truly barren. So far as we know, their diet is much the same as other oryx, and they prefer open terrain with a clear view of the surroundings, avoiding, for example, areas with tall grass.

Like the other oryxes, their diet is dominated by grass. Only around 12% of their diet consists of anything else, including shrubs and roots dug up from the ground in a similar manner to the gemsbok. They live in herds of 30 to 40 individuals, and seem much more mobile than gemsbok, often travelling several miles a night; like their relatives, they can be active at various times throughout the day, only avoiding the worst of the heat.

While some males travel alone, they dominate herds when they live among them. They seem more aggressive than the other species, with fights between males being relatively common, especially when a solitary male tries to muscle in on a herd-living male with an established harem.

Beisa oryx are hunted for their meat and hides, with the latter often being used to make local clothing due to its durability. The great majority live outside of protected areas, and this has led to dramatic declines in their population, which is thought to have dropped to around half of its former number in the first two decades of the 21st century. As a result, even though there are many thousands still remaining - far more than there are of the Arabian oryx - the beisa has been considered an endangered species since 2018.

The scimitar-horned oryx (Oryx dammah) is of similar size to the gemsbok, but has whitish fur over most of the body, fading to a light reddish-brown on the forequarters, and lacking any of the black markings seen in the other species. Even the head has only a single reddish patch on the bridge of the nose, and is otherwise white. It also has much smaller scent glands in front of the eyes, although that is less obvious at a distance. The name, however, comes from the horns, which are marginally longer than those of the gemsbok, and, unlike all other oryxes, are curved, not straight, sweeping back over the body.

Scimitar-horned oryx

It was once found across the entire width of Africa in two broad bands either side of the Sahara, from Morocco to Egypt in the north and from Senegal to Sudan in the south. Here, it inhabited semi-arid grasslands, although the fact that it did not inhabit the Sahara proper indicates it is less of a desert specialist than some of its relatives. Indeed, this part of the world has a distinct rainy season, albeit one where it is not unusual for the rains to fail.

The presence of a rainy season allows the oryx to supplement its usual diet of sandbur, panicgrass and crowfoot grass with saucer-berry, indigo legumes and wild melons. They once travelled for long distances across their range, seeking out areas with recent rainfall, travelling as the weather changed rather than along any particular route. Reports indicated that the largest female led the way, although it remains possible that she was being directed by a male further back in the herd, since males are dominant in other respects. The herds of 10 to 30 individuals travel mostly at night, staying out of the heat, and doing most of their feeding in the early morning before the sun gets too hot. They breed throughout the year except, for some reason, during a one to three-month pause in the spring when the females become temporarily infertile.

The scimitar-horned oryx, however, is no longer as widespread as it once was. The last populations north of the Sahara were wiped out in the early 20th century, leaving only those on the southern side of the desert. This was, and to some extent remains, a politically turbulent area, making any attempts at conservation difficult. Hunting for meat, hides, and trophies was the main pressure on their population, with the decline accelerating as firearms became more common. Numbers declined during World War II, possibly because of the influx of French soldiers, and those that remained took a second big hit during the 1980s civil war in Chad. Expansion of pastoral land for herding livestock, aided by digging wells in the arid landscape, added further pressure, and in 2000, the species was declared to be entirely extinct in the wild.

It had probably actually died out a few years earlier.

Examples did still exist in zoos, however, the animals' rugged physiology and dramatic appearance doubtless helping them. In fact, those that did survive descended from populations across at least the southern part of their former wide range, meaning that they maintained a fair degree of genetic diversity. In 2016, an attempt was made to reintroduce the animals to Chad. Despite this being one of the world's poorest countries, and remaining politically unstable to this day, the animals survived, with new herds being added from zoos over the ten years since.

By 2023, the herds had survived long enough that it was obvious that even wild-born oryxes must have been breeding and raising calves of their own. That, together with a minimum timeframe of five years since the reintroduction started, was enough to allow the species to be lifted out of the "extinct in the wild" category and to become an endangered species - a couple of steps up from where they had been.

We don't know exactly how many are alive today, all of them living in that one area of central Chad, but the 2023 estimate was that there were at least 140, and possibly over 500 at that time. It isn't a lot, but it's better than nothing.

The oryxes are, however, merely four out of the seven recognised species in their particular subfamily of antelopes. Next time, I will be looking at the other three, one of which may be very familiar to certain readers of my non-scientific writing...

[Photos by "pdeley", "MathKnight", Riaan Marais, and Charles J. Sharp, from Wikimedia Commons. Cladogram adapted from Bibi 2013.]

Goo Goo G'joob

2026-07-19T14:08:21.019+01:00

"Pinnipeds" is the technical term for flipper-footed aquatic mammals that are able (although often with difficulty) to move about on land. Although there had previously been some speculation on the point, we now know that they are a natural group of animals, all descending from a single distant ancestor. They are carnivorans, more closely related to dogs than to cats and probably represent the third major branching within the living dog-like carnivores, after the dogs and bears, but before (for example) the raccoons, skunks, and weasels.

The living species of pinniped are placed within three families, although one or two extinct ones are also recognised. Most pinnipeds belong to the Phocidae, or "seal family". While the term "seal" is often used in modern English to refer to pinnipeds in general, the seal family proper consists of animals especially well-adapted to living in the water. They lack visible ears, and their hind limbs are arranged so to be efficient for propulsion underwater, but almost useless on land, forcing them to haul themselves about using their front flippers only.

Almost all the other species belong to the Otariidae, which can loosely be described as the "sea lion family". More accurately, most species in this family are referred to as "fur seals" in English, with there being no clear scientific distinction between what counts as a fur seal and a true sea lion; the names have been applied rather haphazardly. These do have visible ears, and they can walk - or at least waddle - on all fours while on land. Underwater, they propel themselves with their front flippers, using the hind ones for steering, essentially the opposite of how true seals swim.

I have previously discussed the differences between these two families in more detail, as part of a series looking at the "true", phocid, seals. What I didn't talk about in that post, except in passing, is the one species of living pinniped that belongs to neither family.

The walrus (Odobenus rosmarus) is an unusual and distinctive animal. The origin of the common name is most likely an Old Norse word literally translating as "whale-horse". It remains similar in other Germanic languages, as well as those that have borrowed the word from English, although the Romance and Slavic languages have instead tended to borrow the Sami word "morsa". The second half of the scientific name is also Scandinavian in origin, although rather more abused to make it look Latin, and means something like "red whale".

The walrus, perhaps unsurprisingly, appears in the first officially recognised catalogue of scientific names, published in 1758. It helps that it's not just an obviously distinctive animal, but that the list in question was compiled by Carl Linnaeus who, being Swedish, was clearly going to be familiar with them.

At the time, he classified it as one of four known (to him) species of "seal", along with the common harbour seal, the elephant seal, and what we would now call the northern fur seal. Four years later, French zoologist Mathurin Brisson decided it was distinctive enough to be split off from the seals and given its own genus name. This name, Odobenus, means "tooth walker", since he had heard that they sometimes pulled themselves about on land with their teeth. Their further elevation to family status came surprisingly late, in 1880, but only because Linnaeus later changed his mind about it being a seal, and placed it with the manatees; later zoologists seem to have agreed with him, presumably not taking a close look at one or the other animal in the process.

The average walrus is about 3 metres (10 feet) in length, but they are much heavier than one would expect from this figure alone. This is due to an extremely powerful build, perhaps matched only by elephant seals, that means their shoulder girth is almost the same as their body length. A typical female weighs around a ton, while the males are half as much again.

While they are more closely related to sea lions than to true seals, walruses are anatomically intermediate between the two in at least some respects. Like sea lions, they are able to rotate their hind limbs so that they can use them to walk while on land, but, like seals, these hind limbs are their main source of propulsion underwater. However, they do use their front flippers to assist in swimming, paddling as well as using them to steer. Like seals, this is also assisted by muscular undulations of the main body, something that's particularly useful on land because of their great bulk.

The skin of walruses is unusually thick, typically around 4 cm (1½ inches). It is thickest on the neck, especially that of males, where it can reach up to 10 cm (4 inches). This is not counting the insulating blubber beneath, which all pinnipeds possess, and which reaches another 15 cm (6 inches). Walruses do have fur, which is brownish, but it is so sparse that, as with animals like elephants, it isn't immediately obvious at a distance. Adult males have numerous warty nodules around their necks, which may help protect them while fighting, but are more likely to just be something that the females find attractive.

The faces of walruses are distinctive because they are so shortened. They have especially large and thick whiskers, and comparatively small eyes for a pinniped. These are positioned so as to give them partial binocular vision, but it's likely that their vision is relatively poor, albeit with some evidence that they may have some limited colour vision. Like seals, their ears are not visible, opening directly onto the skin without the usual flaps of skin and cartilage that most other mammals possess.

They do have a tail, but it's so short as to be almost invisible, and is hidden by a flap of skin.

Perhaps the most distinctive feature of walruses, however, is their teeth. Since they are carnivorans, their ancestors had the same basic arrangement of teeth that dogs, bears, and the like possess. In their case, however, it has been highly modified, with many of the teeth disappearing altogether. Typically, carnivorans have three sets of incisor teeth in each jaw, but walruses have just a single pair in the upper jaw only, and these are small and rounded.

The lower jaw has four teeth on each side, all of them relatively flat and oval in outline. The first and largest of these is the canine tooth, while the premolars behind them becoming gradually shorter towards the back of the mouth. Like most other pinnipeds, there are typically no molar teeth at all, and there is no hint of the carnassial teeth that are so significant in land-dwelling carnivorans. (I say "typically" here because there is some variation, with some individuals having additional, tiny and rudimentary teeth that raise the total number listed here).

The upper jaw has three sets of premolar teeth, like the lower one, but is most notable for the greatly enlarged canine teeth. These are true "tusks" in the sense that they project outside of the jaw, and they grow continuously throughout life. They can reach a metre (3' 3") in length, and weigh up to 5 kg, and curve slightly backwards to a blunt tip. When they first appear, these have a coating of enamel like any normal teeth, but this soon wears away to leave only the dentin/ivory beneath.

Walruses live only in cold, coastal environments of tha far north. There are two recognised subspecies, of which the more widespread is found from Hudson Bay and the southeastern Canadian Islands, eastward past Greenland to Novaya Zemlya and the Franz Josef islands off the north coast of western Siberia. The second, which is slightly larger on average, lives from the Laptev Sea off eastern Siberia, round to the Chukchi and Bering Seas, including the western and northern coasts of Alaska. Despite that this means many members of both subspecies live in the Arctic Ocean, they are commonly referred to as "Atlantic" and "Pacific" walruses, respectively.

The driving factor here is the walrus's preferred habitat of shallow seas with regular ice floes on which to haul out. While they will use rocky shores if ice isn't available, they do prefer the latter, and may migrate northwards with it during the summer if it doesn't force them into deep water. Ice that's too thick, on the other hand, is also a problem, since they can't break through ice much more than 20 cm (8 inches) thick.

The shallow seas are important because walruses feed on animals that live on the sea floor. While they can dive as deep as 600 m (2,000 feet) if they absolutely have to, 80 m (260 feet) is much more comfortable for them, so a sea deeper than that is less than ideal. Even these dives can last over seven minutes, and they don't seem as exhausting as one might expect, partly due to an ability to store oxygen in their muscles that develops rapidly after birth.

Molluscs are the primary food of walruses, with some studies showing that clams alone provide 81% of their calorie intake. Most of their other food consists of snails and sea worms, with occasional soft-shelled crabs. They search for such food by probing the bottom with their long and sensitive whiskers, sometimes clearing away the mud with their front flippers, then sucking it in using their lips and tongue. On rare occasions, some have even been known to eat seabirds or small seals, although this is probably a case of desperation.

The old belief that they scrape clams off the seabed using their tusks is a myth, perhaps arising because they do sometimes prop themselves up with their tusks while feeding.

There have been few studies conducted on the social lives of walruses, and what there have been suggest that there isn't much of it to look at. Walruses aren't antisocial and will gather together on ice floes or rocky shorelines, but neither do they seem particularly sociable, in the sense of really interacting with one another outside of the breeding season. They do not, for instance, make much in the way of noise to communicate, and they could hardly leave scent marks, living where they do. But, without detailed studies to show otherwise, it's always possible that there's plenty we're missing.

The exception, however, is during the winter breeding season. At this time of year, the males compete with each other to impregnate as many females as possible, and may establish a temporary dominance hierarchy to do so, much as other pinnipeds do. This is largely achieved by puffing themselves up to look impressive and then shouting at each other. These are loud, booming or bell-like sounds, which they can make thanks to the presence of two large sacs on either side of their windpipe, which are absent in the females. If this fails, they will get into physical combat with their tusks, but this is comparatively uncommon.

Possibly attracted by the calls, the females gather around and mating takes place in the water. This may be aided by the fact that the male has an unusually long, 60 cm (24 inch), bone in his penis to provide added support.

Pregnancy lasts a full 15 months, and almost always results in the birth of a single young. While still in the womb, the baby develops the same white fluffy coat that newborn seals have, but this is shed before they are born, so that they initially look like miniature, tuskless adults. This means that, unlike seals, baby walruses are able to swim from the moment they are born. In another exception to the general lack of vocal communication, the mother regularly barks to her infant to bond with it and ensure it does not get lost.

Initially weighing about 60 kg (130 lbs), the young walrus grows rapidly, but stays with its mother for up to two years before striking out on its own. As a result, females give birth, at most, once every two years, half the rate we see in other pinnipeds, and usually less often than that. While walrus milk is not quite as nutritious as true seal milk, perhaps partly because of this slower development, it is still richer than that of most land mammals. Unusually, baby walruses can suckle while their mother is swimming at sea, something that would be pointless in seals, which are not born able to enter the water.

Historically, walruses were widely hunted for their meat and tusks, leading to dramatic declines in the Atlantic population. This has greatly declined since the 1990s, although it is allowed at very low levels in a few indigenous communities. Today, the worldwide population is thought to be over 100,000 and is more threatened by melting sea ice and the development of shallow waters for oil and gas drilling. As a result, while it isn't formally considered an endangered species, it isn't a wholly safe one, either.

[Photo by Joel Garlich-Miller, of the U.S. Fish and Wildlife Service. In the public domain.]

Synapsida takes a break next week, but will be back in August.

Euplerids: Madagascar's Top Mammalian Carnivore

2026-07-12T13:22:31.030+01:00

The native mammalian carnivores of Madagascar are mostly obscure to those of us in the West. The one possible exception, thanks to the Madagascar animated film franchise, is the fossa (Cryptoprocta ferox). Often spelt with a single 's', especially in more modern sources, and typically pronounced "foosa", this is the largest and most potentially dangerous of all the island's native mammalian predators.

Having said which, it's not especially big compared with predators elsewhere. There is little need to be a large carnivore when the island does not have, for example, any native antelopes. On average, they are about 75 cm (30 inches) in body length, not counting a cat-like tail that adds about the same length again. Adult females weigh around 6 kg (13 lbs), while the largest males can reach 8.5 kg (19 lbs), about the same as a West Highland terrier.

Exactly where they fit within the mammalian family tree was long a source of confusion, given a mix of features resembling a range of other animals. When English zoologist Edward Turner Bennett first described the animal in 1833, he considered it to be a type of unusually large civet. So it remained for a hundred until it was moved to the cats in the 1930s, back to the civets in the 1940s, and then to the mongooses in the 1990s. Over the next ten years or so, arguments continued back and forth between all three of these options until genetic studies finally settled the matter in 2003.

As has been confirmed by other studies since, the fossa is a euplerid, descended from the same original ancestor as all other Madagascan carnivorans. It isn't even a separate subfamily within that group, as had been suspected, being more closely related to the falanoucs and fanalokas than to the vontsiras.

A lot of the confusion, in the days before genetic studies, comes from its odd appearance. While it may be much smaller, it looks a lot like a puma/cougar/mountain lion, albeit with a slightly longer, more pointed face. The nose is prominent, like that of civets and mongooses, but the ears are catlike. The paws are large, with hairless soles and partially retractile claws; like many tree-climbing animals, they can twist their ankles backwards to make it easier to move down head-first.

A more bizarre adaptation, unique to fossas so far as we know, is that young females have male-like anatomy, but this fades as they reach full adulthood. This includes the presence of a secretory gland on the abdomen that is otherwise only functional in males, and an enlarged, penis-like clitoris, complete with foreskin and containing a spiky internal bone. (The presence of a clitoral bone, or baubellum, is not unusual in mammals, although it's absent in apes and humans and is usually very small). How this happens, and why, remains a mystery, although it doesn't seem to have anything to do with the presence of male hormones.

Fossas are forest-dwelling animals, but they seem equally at home in the semi-arid forests of the west as in the damp tropical jungles of the east, with the result that they are found essentially across all of the coastal regions of the island, with a few reports from the scattered patches of woodland that still remain in the interior - most of which have otherwise been cut down for farmland. They are, however, present at lower population densities than we would predict based on similar animals elsewhere, perhaps as a result of the breakup of larger patches of woodland.

Unusually, they appear to be equally active day or night, perhaps changing their habits based on the presence of humans, but otherwise sleeping whenever they feel like it, regardless of the position of the sun.

Although active on the ground, they are also adept at climbing trees, a useful trait when so much of their potential prey is arboreal. In captivity, they will eat almost any meat provided to them, and their diet seems similarly opportunistic in the wild. For most of their range, this inevitably means that their main prey is lemurs, which have essentially no other mammalian predators. In at least some areas, half of the animals eaten by fossas are lemurs and, since lemurs are larger than most of the alternatives, that would be a much higher proportion of their food by weight. Their largest prey are sifakas, a type of lemur that can weigh about 90% as much as the fossa itself.

Their second favoured prey seems to be the shrew-like and hedgehog-like tenrecs native to the island, but they will also eat other animals, including snakes and crabs, if those are what happen to be around. Although they don't like to travel far from trees, they will venture into farmland, where they eat chickens and even young goats. Although it's difficult to make such an assessment objectively, this has led to their reputation as the deadliest mammalian predator on Earth, relative to their size.

Like their relatives, fossas are solitary animals, although their larger size allows them to range across wider areas of forest. The typical home range of any given individual likely varies depending on where on the island it lives, and how far it will have to travel to keep fed, but some studies give surprisingly large figures of 55 km² (21 square miles) or more, with males travelling further than females. While they do scent mark their territories, using similar glands to those on other euplerids, individual ranges can often overlap, so they are likely not as territorial as one might expect. There are also some reports of pairs of males cooperating where their ranges overlap, even though fossas are normally solitary except for females travelling with young.

Mating is seasonal, taking place between September and December. Receptive females are often surrounded by groups of up to eight males, fighting for access in one of the few instances where they will make any noise towards one another. Even so, it seems to be the female who picks her partner, although on what basis is unclear.

Mating often, but not always, takes place up a tree to limit the chance of interruption. This is important, because the mating act takes at least an hour, during which the partners are locked together in a copulatory tie, as happens with dogs, which would obviously make it difficult for them to do much else. You would think that an hour would be quite long enough to satisfy both partners, but apparently not, as they will engage in several bouts over a period of up to 14 hours in total. Even then, the female may pick a different partner on the following day and continue for up to a week.

Exhausting, one would think.

Most offspring are twins, although singletons and larger litters also occur. Like other euplerids, the young are born blind and helpless, in their case with white fur. They grow relatively slowly to begin with, not opening their eyes for two to three weeks, by which time their fur has reached a pearl-grey colour. They only begin to become independent at four to five months, finally leaving home as the following year's breeding season approaches.

The number of fossas is declining due to a reduction in forested land in Madagascar and active persecution by farmers concerned about their livestock. Population estimates can be as high as 8,000 but the current number is likely quite a lot lower than this, and the animal is officially listed as vulnerable, although not quite endangered.

However, it is now thought that there were once two species of fossa on Madagascar. The other was the "giant fossa" (Cryptoprocta spelea), identified from subfossil remains in 1902. For a long time, it was not clear whether this was really a distinct species, and the debate still is not entirely settled, but the current consensus is that it genuinely was. With no true fossil sites on the island that might give us more of a picture, we can only say that it must have survived the Ice Ages, and we don't even know when it went extinct, other than that it must have been before Europeans reached the island in 1500. Given the age of the only known specimens, it might even have been before the native humans reached the island around 550 BC, but, again, we don't know.

One of the reasons for regarding the giant fossa as a distinct species is that, based on the remains we have, it seems to have been a bit too large to simply represent big specimens of the living species. They were about 30% longer than the living animal, giving weight estimates of at least 17 kg (37 lbs). It would have preyed on large lemurs, as some crocodiles and large birds of prey do on the island today. While its remains have not been found where we would expect crocodiles to be common, suggesting some degree of justifiable fear on its part, it may have eaten sufficiently different prey to share its territory with the modern species, allowing the two to live alongside one another.

[Photo by Chad Teer, from Wikimedia Commons. Cladogram adapted from Yoder et al. 2003.]

The First Cows In Europe?

2026-07-05T14:56:29.313+01:00

When we look at scientific lists of animals, we usually see them placed into neat groups based on their relationships: families, subfamilies, and so on. These are, however, entirely human constructions, and nature is rarely so tidy in reality. Even for mammals, which have been more thoroughly studied than, say, fish or invertebrates, disagreements can arise, and details can change.

At least in the case of mammal groups above the species level, the relationships are faily well understood by this point, thanks to the advance in molecular and genetic studies over the last couple of decades. Disputes are more likely to arise when we question how broadly we should define a particular group, and what taxonomic level it might have. (The latter, of course, are entirely artificial; the cat family is provably a 'real' thing, but the fact that we call it a 'family' rather than giving it some other rank is essentially arbitrary).

This becomes a much bigger issue when we look at animals we know only from fossils. For one thing, we will have fewer, and generally less complete, specimens to examine. Furthermore, unless they are really recent, genetic analysis is out of the question. But, on top of all of that, when we travel back in time, lines become inherently blurred. There's always going to be the question of where exactly the 'not yet X' becomes 'X', even if we had perfect information about them. Which we don't.

Bovines are considered a subfamily within the larger cattle family, which also includes antelopes, sheep, and goats. I've previously looked at the various living bovine species in a series on this blog, and there, I noted that there are three main branches within the subfamily. The two most important of these today are the bovins (cattle, bison, buffalo, yak, etc.) and the tragelaphins (spiral-horned antelopes), with the first of those being characterised, among other features, by a particular heavy build.

It is now generally agreed that the bovins evolved around the end of the Miocene from animals currently placed in the third 'tribe' of living bovines: the boselaphins. These are represented today by just two species, the nilgai and the four-horned antelope but, obviously, neither of these are the actual ancestor of cows and bison. Indeed, the use of the term 'boselaphin' to describe these putative ancestors is really just one of convenience. It's almost certain that that isn't literally what they were, just that they happened to look similar, and we haven't got a better word for them.

Either way, we can ask the question of when the whatever-they-were turned into bovins as we understand them. And any answer to that question is going to be messy. In the case of Europe, for example, there has been considerable debate as to when bovins first reached the continent, driven largely by the relevant fossils being too rare and incomplete for it to be apparent whether they actually are early bovins, or late survivors of their ancestors.

At least, until recently.

Camps del Ninots is a fossil site in northeastern Spain, just south of Girona. It was formed by a volcanic eruption that occurred when rising lava hit a layer of deep groundwater. The resulting explosion of steam and molten rock blasted a hole in the ground 1 km (1,000 yards) across that was partially filled with water to form a lake. Sediment built up at the bottom of the lake with just the right anoxic environment to preserve animals that ended up there as unusually complete and well-preserved fossils - a lagerstatte.

The latest dating places the rock strata that now lie where the lake once was as having been laid down during the early Pliocene, about 4.4. million years ago. We have been excavating the site for over 20 years now, uncovering all sorts of vertebrate fossils, including fish and frogs as well as land animals. Among the large land mammals, three species stand out: a rhinoceros, a tapir, and, of more relevance to today's post, a bovine.

The fossils in question were assigned to the relatively obscure genus Alephis. This is otherwise known mainly from southern France, northern Italy, and elsewhere in Spain, with possible fragmentary remains from Greece and Slovakia and even some from southern England. Historically, both this and its close relative Parabos, lie at the heart of the question of where the line between bovins and early 'boselaphins' should be drawn.

About a month ago, a study was published examining the fossils of at least 14 individuals, some of them remarkably complete and well-articulated. As always, we can never say that this is the last word on the matter, not least because answers to these sorts of questions will always come down, at least in part, to personal interpretation. But we can certainly say that it tells us something.

Perhaps the first finding of significance is that the researchers believe that the species in question doesn't belong to Alephis at all, but to Parabos. This was first defined in 1929, to include two known fossil species that had previously been placed with blackbucks, in what is now the gazelle subfamily. With at least five species already known, Parabos lived in much the same geographical area as Alephis, with fossils known from southern Spain across Europe to as far east as Moldova and Turkey.

The fossils reveal a heavily built, antelope-like animal with slightly curved horns facing backwards on its head, giving it an appearance similar to that of the living anoa, or dwarf buffalo, of Sulawesi. However, it was quite a lot larger than those are, with an estimated average body mass of 420 kg (925 lbs), similar to, say, a female red deer or elk. This would, in fact, have made it the largest known European "antelope" of its day, and perhaps of the entire Pliocene. The average weight, however, conceals a degree of variation, suggesting that males may have been larger than females, although not to the extent seen in living species of bovin today.

Features of the horns, along with other aspects of the skeleton, indicate that the animal did not fit neatly within either the modern bovins or the early European 'boselaphins' such as Tragoportax. In fact, it had some unique features in common with both, suggesting an intermediate form. The authors of the study prefer the idea that it is closer to the bovins, partly because of its relatively large size, and partly because female Tragoportax were hornless, which none of these animals are. Still, they concede that it could also be a case of parallel evolution among the last gasp of a separate lineage. It's likely, here, among the fuzzy lines between groups (one of which is long extinct), that future debates will end up being focused.

The climate in Spain at the time the animal lived was warm temperate to subtropical and relatively humid. The lake within which the fossils were found is known to have been surrounded by broad-leaved woodland and small streams, with conifers on the higher slopes. This fits with the sort of habitat that the 'boselaphins' are thought to have favoured, rather than the more open, grassy plains preferred by the likes of living bison. However, here again, the teeth of this species of Parabos suggest a somewhat mixed diet, not as browse-based as its putative ancestors, but not yet as heavy on grass as bovins would later be.

The shape of the animal also fits with a forested environment, since it doesn't look to have been capable of fast running. For defence, it may have partly relied on its large size for the time, and the females having horns would doubtless have helped, too.

These are not the ancestors of today's European bovins, since undoubted 'true' bovins, such as Ugandax, already lived in Africa at the time, where they appear to have evolved partly in response to the expansion of local grasslands. But they could be the first example to enter the continent, some early offshoot coming across, likely via Asia, and thriving in a habitat just a little too damp and heavily wooded for their larger, more modern-looking kin. But, equally, they could be examples of local forest animals developing larger size and bovin-like features in an attempt to survive as the climate changed towards something that would, in the longer run, favour aurochs and European bison.

The answer as to which remains, as it so often does, fuzzy.

[Picture by Leonardo Sorbelli, available under CC-BY-4.0, cropped from the original.]

Two Million Years of Llamas

2026-06-28T14:07:28.730+01:00

The camel family is one of the smaller mammal families in the present day, containing just seven species, four of which are domesticated. Thus, if you don't consider, say, dogs to be distinct from wolves at the species level, one could reasonably argue that there are only four. Although these are all considered to belong to the same subfamily (with all the other subfamilies being extinct), they still fall into two branches: the 'true' camels in the Old World, and their counterparts in the Americas.

It should come as no surprise that members of the family are noted for their ability to survive in arid environments with minimal water. They are, for example, more efficient at absorbing water from their stomach than ruminants such as cattle and deer, and genetically resistant to heat stress and ultraviolet radiation. Nonetheless, while the word "camel" doubtless conjures up an image of one or more of the three Old World species (that is, the dromedary and the wild and domesticated versions of the Bactrian camel), the family also includes those four American species.

Technically referred to as lamins, these are the domesticated llama and alpaca, and their respective wild ancestors, the guanaco (Lama guanicoe) and vicuña (Vicugna vicugna). Evidence suggests that these two wild species last shared a common ancestor between two and three million years ago, at, or shortly before, the start of the Ice Ages. This is relatively recent, and they can still crossbreed, so that all four species are often placed in the same genus, Lama. Indeed, modern domesticated alpacas share several genes inherited from interbreeding with llamas, albeit this mostly seems to have happened after the Spanish conquest of South America, long after the initial domestication event.

Camels, however, originated in neither Asia nor South America, but North America. While the ancestors of the true camels probably entered Asia relatively early on, towards the end of the Miocene, the ancestral members of the llama group only reached South America when the Panama land bridge first joined the two continents around 2.7 million years ago. Which, you will note, more or less matches the time of the split between the two living genera.

At the time, however, they were not alone. There were many types of 'camel' in North America at the time, and several of them seem to have headed south when the newly reachable continent opened up opportunities. Back home, a combination of the Ice Ages and the arrival of humans finished them off, leaving just those who had already moved elsewhere surviving, in Asia, Africa, and South America.

But that still left far more llama-like animals in South America than there are today. In fact, over thirty different fossil species have been named at one point or another, although it's inevitable that some of these will turn out to be misidentifications of something already named, so that the actual number won't be quite that high. And we are talking a timespan of over two and a half million years, so it isn't as if they were all alive at the same time.

But, with the help of a recently published review of their history, we can put together a picture of what happened to all of those missing llama-like species, and how the surviving ones got to where they are.

Perhaps the first question is why the two living species survived the end of the Ice Ages, when all the others didn't. In the case of the guanaco, this may be down to its adaptability. True, both species are capable of living in harsh environments, but guanacos have a wider diet and can tolerate a wide range of different harsh habitats. Today, they are found wild in the Andes as far north as Peru, but also widely across the lowlands to the east, reaching all the way through Patagonia to the southern coast of Tierra del Fuego, as close to Antarctica as you can get without swimming.

The vicuña, on the other hand, had a harder time of it. The oldest vicuña fossils date from around the middle of the Ice Ages, while guanaco fossils are slightly older, but we can tell that, for much of that time, they, too, lived in Patagonia. Indeed, the so-called "slender llama" (Lama gracilis), an extinct species, has recently been reclassified as just being a regular vicuña, and we know of fossils fitting that description not far from Cape Horn, just like guanacos.

They died out there around 13,000 BC, shortly before the end of the Last Ice Age and today are found only in the high Andes, from Peru to northern Chile. This may be because they are more selective feeders, preferring specific grasses that are adapted to cold, dry environments and the lowlands may simply have become too warm for their favourite food. They retreated to refuges in the mountains, where a previous mild period meant they were already established and, being far less willing to travel long distances than guanacos are, they basically stayed there.

There were relatively few other llama-like animals in Patagonia at the time, although the comparatively large Owen's llama (Lama oweni) may have been one of them. This, and the last of the South American horses in the region died out between 12,700 and 11,000 BC. Two things were happening at this time and they were both probably relevant. Firstly, the warming that had disadvantaged the vicuñas ended with a dramatic cold snap known as the Antarctic Cold Reversal that saw the landscape change to icy tundra.

Secondly... well, human hunters got there, and that's never good.

As for the central Andes, the oldest known vicuña fossils are from this region, dated to around 80,000 years ago, so they were already well-established by the time they were driven out of Patagonia. Guanacos had been there longer, going back 780,000 years, although Palaeolama had been there even earlier. Even the guanaco, however, had been there long enough that it must have moved about over the course of hundreds of millennia as Ice Ages came and went.

At the height of the last one, for example, the local climate changed enough that there were lakes in the Atacama Desert, which, paradoxically, might have forced the arid-adapted vicuña up onto higher ground to the north. Over time, they developed adaptations to improve their ability to live at high altitude, such as large hearts and blood that is more efficient at absorbing scarce oxygen, which, given the lack of competition, gave them even less reason to leave.

Humans reached this, relatively inhospitable, part of the world only around 7,000 BC and are known to have actively hunted both guanacos and vicuña from at least 4,000 BC. That this wasn't similarly disastrous may be down to the fact that llamas and alpacas were first domesticated from their wild ancestors at around the same time, giving farming communities ready access to an alternative.

Further east lies the Pampas, the grassy savannah habitat south of the Amazon in northern Argentina, Uruguay, and southern Brazil. This too, underwent changes in climate over the years, which would surely have affected the animals living there. While it's too far north for guanacos today, they did live there for some of this time, although the more dominant species would have been those belonging to the genus Palaeolama, which was larger than modern llamas, and probably more able to subsist on forest browse than merely on grass. Eulamaops, a lesser-known genus about the size of today's largest llamas, lived alongside it.

A shift towards warmer and more forested environments as the Ice Ages came to an end should have been good news for both of these extinct forms, but by then, humans had reached the area, and neither survived, with Palaeolama dying out perhaps as recently as 1,500 BC. Going back further however, this was also the region where Hemiauchenia, potentially the common ancestor of guanacos and vicuñas, had lived after it entered South America from the northern continent.

Hemiauchenia is also known from North America, where a great many other llama relatives lived that never chose to move south. By doing so, however, while it has long passed from the world, its presumed descendants lived on, ultimately receiving what may be one of the best guarantees of survival in the modern world: becoming a useful domesticated animal.

[Photo by "Goliath" from Wikimedia Commons.]

The Genomics of Yellow Bats

2026-06-21T15:59:17.252+01:00

In terms of species, bats are the second-largest order of mammals, after the rodents. New species are identified all the time, due in part to the relative difficulty of closely examining night-flying mammals, many of which sleep in hard-to-access caves. The current total stands at over a thousand, representing over 20% of all known mammal species.

Within this huge group, there is, perhaps, rather more diversity than many people realise. While bats have probably not received the same level of attention as some other mammal groups, scientists have nonetheless long attempted to disentangle the relationships between all these subgroups. (Also, when I say they have received less attention, there's a mammal-centric bias here; it's probably still a lot better than, say lizards, let alone millipedes or the like).

In the past, we identified different species by their physical appearance and, with bats, we have the added ability to examine differences in their ultrasound calls. While we used this information to make some inferences about which bats might be more closely related to others, there were limits as to how much we could do this without relying on mere guesswork. Today, of course, we have genetic analysis, looking at how invisible changes have occurred in genes as animals evolved, tracing relationships we could never see before. Over the last two decades, this has continued to improve as we become able to sample larger and larger sets of genes and use increasing computing power to spot common patterns in the correspondingly vast databases we build up.

These sorts of analyses have enabled us to confirm that the 21 recognised families of bat are, indeed, distinct evolutionary lineages, and how they relate to one another. This has helped us understand how and when echolocation evolved, with most modern studies suggesting that echolocating bats do not share a unique common ancestor. (Thus, it either evolved twice or one subgroup later lost the ability.)

At a higher level, we have been able to determine how bats relate to other mammals. The general consensus here is that they are something of a side branch, splitting off from the group that would later lead to both carnivorans and hoofed mammals before they even split from each other.

At the opposite end of the scale, however, things can often be more intractable. Twenty years ago, when we could only compare single genes across multiple species, this wasn't such an issue. But improved modern methods, while promising more accurate detail, produce correspondingly more data, making them hard to compare across a large group. This is especially true of the vesper bat family, partly because it's the largest of all the bat families, but also because it underwent a rapid burst of diversity around 35 million years ago, at the dawn of the Oligocene. Such rapid changes are difficult to disentangle, since the key thing you want to know is what order they happened in - and they almost (but not quite) happened all at once.

However, it is possible to perform these sorts of analyses on smaller numbers of closely related species. This provides a different kind of information than that we get from the "big picture" studies of how families and orders relate. Instead, it can reveal how species responded to climatic changes such as the Ice Ages, and how geography, dispersal behaviour, and vicarious events led to them being what (and where) they are now.

While it isn't the first of its kind, one such study was published in April, looking specifically at a group commonly known as the yellow bats. There is some debate as to exactly how these particular bats should be classified. We know that they are distinct evolutionary group, more closely related to each other than to anything else, and we also know that their closest relatives are the red bats (Lasiurus spp.)

The argument purely concerns whether they are different enough from the red bats to be given their own genus or not. While the case has been made, so has the counter-argument that there's just no need, and, as of this writing, this is the stance taken by sources such as the American Society of Mammalogists and the Batnames Database, and that I will therefore be using here.

That aside, what we can agree is that there are four currently recognised species of yellow bat. The northern yellow bat (Lasiurus intermedius) lives in southern and eastern Mexico and along the southern coastal regions of the US from Texas to South Carolina, with two isolated populations further north along the Atlantic seaboard, the most northerly reaching the outskirts of New York city. The western yellow bat (Lasiurus xanthinus) inhabits northern and central Mexico and the border regions of the US as far north as Los Angeles. The southern species (Lasiurus ega) is the most widespread, being found through southern Mexico, Central America, Colombia and Peru west of the Andes and almost the whole of the rest of the continent on the eastern side, reaching as far south as northern Argentina.

These were all discovered and named in the 19th century, although the western yellow bat was not raised to full species status until 1988. More recently, an additional, rarer species, the Cuban yellow bat (Lasiurus insularis), being split off from the northern species in 1995 and living only in its eponymous island country. They are all fairly regular-looking bats aside from their yellowish fur, and live in forests and patches of semi-arid woodland, where they roost in trees during the day - most often palm trees or amongst Spanish moss, although it depends exactly where they live. They feed on bugs, flies, beetles, and other flying insects.

The researchers took samples from 125 specimens stored in natural history museums from across the bats' ranges and looked at sequences across the genome, allowing for more thorough coverage than had been possible with earlier methods. They then used specialised software to analyse the differences between the samples, making it possible to build up a family tree and, by calibrating against the known age of relevant fossils, provide an estimate of when different branches of that tree appeared.

The overall picture this produced matched that from most earlier studies, with the Cuban and northern species being the most closely related. Even this much is a positive, however, since a 2020 study had seemed to indicate that the Cuban yellow bat couldn't be a distinct species after all. By sampling a wider section of the genome to obtain a complete picture, this seems to put that one to bed. Which is good news for the Cuban bats, since their low population and declining, exposed, habitat make them a Vulnerable species, a conservation status they would lose if they weren't a species in the first place.

The dates are, however, perhaps more significant. The Cuban bats diverged from their mainland kin 1.25 million years ago, during the Ice Ages, while their common ancestor split from the southern species 3 million years ago, in the Late Pliocene (the "long autumn" before the Ice Ages).

Interestingly, the study also threw up some ancestral branching within the southern yellow bats. The ancestors of the bats from Ecuador seem to have split from the ancestors of other sampled members of the species over 1.5 million years ago, well before the Cuban bats became a species. While it may be a stretch, based on this alone, to argue that the Ecuadorian bats represent a previously unknown species, if distinct physical differences could be identified, describing them as a "new" subspecies may be perfectly justifiable. (The two known subspecies of the northern yellow bat, incidentally, show up clearly in the data, having diverged 780,000 years ago, while the currently recognised southern subspecies do not, and may not really exist.)

The western yellow bats are the oldest species, as had previously been suspected, with the estimated divergence time here being a little over 5 million years ago, very roughly at the Miocene/Pliocene boundary. Because such studies include closely related animals outside of the group being studied in order to calibrate the starting point, it's also possible to say that the common ancestor of yellow bats diverged from that of the other red bats over 13 million years ago, marking the origin of the group. (Doubtless, those arguing for a separate yellow bat genus will be heartened by this, because it is very early for a group smaller than a genus, but it's no clincher).

These dates, combined with what we know of ancient climates, allow us to build a picture of how this one small group of mammals evolved. The researchers believe that yellow bats first evolved in North America, and began to branch into different species when some of them (later the western bats) adapted to drier conditions than the others.

Suitable habitat would have been available to them in South America from the Pliocene onwards, but only in the south of the continent, so it seems unlikely they reached it until the Ice Ages. The cooling climate forced the bats further south, leading to the distribution we have today. Similarly, warmer periods between the Ice Ages would have allowed them to move north and inland, into regions where they no longer live. Indeed, in the 1960s, a fossil identified as belonging to a yellow bat was discovered in Kansas, and dated to the last interglacial, 120,000 years ago.

Of course, this is just one small group of mammals, and not one of great significance to many people. They are not of noticeable economic importance, and only the Cuban yellow bat, which we already knew was distinct, is under any known conservation threat. But it illustrates a principle, of how advancing scientific techniques - in this case, genomics - can lead to new understanding, bringing a picture of the world's past into clearer view.

[Photo by Juan Corzado Cortés, from Wikimedia Commons.]

Euplerids: Falanoucs and Fanalokas

2026-06-14T13:57:42.052+01:00

Fanaloka

The relationships of the native Madagascan carnivores were uncertain before the advent of genetic testing at the end of the 20th century. The majority were assumed to be mongooses, since that is very much what they looked like, but three species didn't quite fit the pattern.

Two of these were, so far as anyone could tell from their physical appearance and habits, civets. They were often placed in their own subfamily, reflecting their distance from other civets, but nonetheless, they were thought to belong among the viverrids. Following genetic studies in 2003, however, it became clear that they belonged in the same group as (i.e. shared a unique common ancestor with) the Madagascan "mongooses". Since some of them clearly weren't mongooses, and since they had diverged from the real ones so long ago, the subfamily was split off and promoted to full family level, now including both the mongoose-like and civet-like species.

To avoid confusion, this meant that the civet-like species needed new names. Following the usual modern method for doing such things, scientists simply borrowed the local names for the animals ("civet" comes from Arabic, "mongoose" from Marathi). Thus, the species formerly known simply as the "Malagasy civet" became the fanaloka (Fossa fossana).

To be fair, the name still isn't universally used, even in sources written this century. Indeed, there are also variants on the name, such as "striped civet" and "spotted fanaloka" - as if there is some non-spotted counterpart to compare it with - the profusion of which may be linked to the animal's relative obscurity outside of its homeland.

The fanaloka is quite a bit larger than any of the vontsiras, although it is also smaller than any living species of civet. Adults reach about 40 to 45 cm (16 to 18 inches) in body length, with the largest males weighing just under 2 kg (about 4 lbs); twice the weight of a vontsira but less than half that of a domestic cat, or of most civets. (Or at least, this is what the few recorded measurements show; they were taken during the dry season when animals may have been underweight.) They have a pale brownish coat, marked with a pair of dark stripes down the back, flanked by a series of increasingly broken lines that eventually peter out into a row of spots.

Despite the smaller size, fanalokas have a body form that resembles that of a civet far more than a mongoose and, for example, they have noticeably shorter tails than vontsiras. They also have anal scent glands, as civets do, although they may use the glands on their face and neck at least as much when scent marking to leave messages for one another.

They live along the eastern side of Madagascar, where the thickest forests remain. Although they will tolerate a wide range of woodland types (at least, among those found on the island) they prefer areas with plenty of available water, and avoid areas with heavy logging or similar disruption. Where they are found, they can be amongst the most common native carnivores, rivalling the ring-tailed vontsiras with population densities of three individuals per square kilometre (8 per square mile) in the most suitable forests.

They are nocturnal, sleeping through the day in tree hollows or rock crevices in cliffsides and, like most of their close relatives, do not seem especially sociable. One of the few studies on their diet indicated that they primarily feed on aquatic or semi-aquatic animals. Frogs and crabs were the most common large prey animals found in their dung, followed by rodents and swamp-dwelling tenrecs (local, shrew-like mammals). These are accompanied by many invertebrates, including grasshoppers, beetles, and millipedes. However, we are again limited by the small number of studies, since this one was conducted in a particularly damp jungle. Granted, this is where they prefer to live, but they have also been recorded in places with no nearby standing water at all, so they are probably quite willing to eat other foods if they have to.

Their lives are more tuned to the seasons than is often the case in the tropics, due to the presence of a distinct dry season between August and November. (Although, on the humid east coast where fanalokas live, "dry season" is very much a relative term...) During this time, fanalokas store fat in their tails as a reserve, which can comprise as much as a quarter of their total body weight. It's also when they breed, ensuring that the young are born when the rains become heavier again. This results in a single young at a time, born with its eyes open and reasonably active, being able to walk at three days, and weaned by two and a half months.

Falanouc

The other species formerly identified as a civet was split into two in 2010, although the respective forms had been recognised as subspecies since the 1920s. By far the more common of the two is the eastern falanouc (Eupleres goudotii), the species for which the former subfamily was originally named in 1835.

This lives in much the same area as the fanaloka, and has a similar habitat too, although perhaps with an even greater preference for swampy terrain. They are similar in general form, having the same scent glands and ability to store fat in their tail, but they are slightly larger and notably more muscular, often reaching weights of 2.1 kg (4 lbs 10 oz.). Their coat is a much more uniform reddish-brown colour, lacking spots and only fading on the animal's underparts.

Their feet are comparatively large and bear strong and powerful claws that reach the ground when they are walking. One might think that this would be because they are aggressive predators, tearing at the flesh of their victims, but they aren't. This becomes apparent when one looks at their teeth, which, unlike the claws, are unusually small and lack the shearing surfaces required to slice tough meat.

In fact, the few studies of their diet indicate that they eat little but earthworms, although supplemented by other invertebrates and probable carrion from small reptiles and the like. There are also some anecdotal reports that they consume fruit. In short, they are carnivores that have adapted to soft-bodied, defenceless prey. The claws are most likely there to dig into the soil in search of food, although they can use them defensively if they have to. While they presumably could also dig at least shallow burrows, they don't, instead sleeping in tree hollows. Having said which, while younger individuals can climb trees to find shelter, fully grown adults either can't or won't, selecting hollows at the base of tree trunks rather than those higher up.

The few observations of falanoucs in the wild suggest that they can be active at any time of day or night, with little obvious preference for either. While they can fight in self-defence, if they do spot a threat, they are more likely to simply freeze in place, remaining motionless for up to an hour. They have generally only been seen alone, and so are likely antisocial outside the breeding season, and they seem to make few noises, communicating a desire to mate by leaving scent marks, but little else. Reproduction is, so far as is known, similar to that of fanalokas.

If we know little about the eastern falanouc, we know even less about the western falanouc (Eupleres major). It is larger and more darkly furred than its eastern cousin, and lives in a few scattered forests in the northwest of the island, preferring, but not being restricted to, those with regular access to fresh surface water. Given that they were thought to be the same species until 2010, it is likely that it is very similar to its close relative, in support of which, it is thought to mainly eat earthworms and slugs.

One thing we can say is that the western falanouc is rare. That's partly because of it being restricted to a few relatively small forests, but also due to competition from feral cats and dogs, logging of the few forests that remain, and hunting for bushmeat. Thus, while we have no idea how many of the animals remain, the species is officially listed as endangered and a lack of local funding for conservation means that that is unlikely to change any time soon.

There is, however, one further member of the Madagascan carnivores that resembles neither a mongoose nor a civet, and whose placement was long considered puzzling until it was discovered to be a close relative of the fanaloka. Perhaps the best-known mammalian predator on the island, it confusingly happens to have a common name identical to the scientific name of the fanaloka's genus. Next time, I will take a look at that, concluding this particular series.

[Photo by Charles J. Sharp, from Wikimedia Commons, and drawing by Joseph Smit, in the public domain.]

Eocene (Pt 4): Ancient Beasts of the European Archipelago

2026-06-07T16:40:22.474+01:00

Propalaeotherium

The story of the evolution of the horse is one of the most commonly cited examples of evolutionary trends, often illustrated by a series of increasingly horse-like animals with an ever-reducing number of toes. The animal typically shown at the start of that series is, depending partly on the age of the picture, either Hyracotherium or Eohippus.

Hyracotherium was long regarded as the earliest known member of the horse family. In recent decades, it has become apparent that it wasn't really a horse, in the sense that modern horses don't descend from it or its relatives, and today we call the family it belonged to the palaeotheres. The North American Eohippus, on the other hand, despite long being thought to be identical to Hyracotherium, probably is a horse. The confusion between the two means that it's often difficult to tell which is being referred to in older sources.

Fortunately, there are other palaeotheres that, while less famous, have been much better studied. Hyracotherium is one of the earliest forms, somewhere between the size of a cat and a fox, and was originally discovered in southern England. Its contemporaries include Eurohippus from Germany (for which we even have the fossil of a pregnant mother) and Propaleotherium, which was more widely distributed across what was, at the time, the European archipelago. The latter was one of the larger palaeotheres of its day, standing as much as 60 cm (2 feet) tall at the shoulder. Remarkably, we have fossilised gut contents from one specimen, which indicate that it was a fairly indiscriminate eater, feeding on a mix of leaves, fruit, and seeds.

The palaeotheres may not have been horses even in a general taxonomic sense, but they were more closely related to horses than to anything else alive today. Although we do know of some from Asia that appear to have been less successful in the long run, the great majority lived only in Europe. There, isolated from the outside world, they continued to evolve separately from their equid kin in North America. While some reached as far as Greece, they were, by this point, mostly restricted to western Europe, with a particularly large number of unique species found on the island that would later become Spain and Portugal.

These later palaeotheres became much larger than the early forms. While the smallest species of Plagiolophus were no larger than Hyracotherium, the largest may have reached up to 150 kg and stood about a metre (3 feet) tall at the shoulder. Palaeotherium, for which the family is named, was larger still, with one estimate for the largest species putting it at 700 kg (1,500 lbs), which would make it larger than most modern horses.

While the earlier species had four toes on the front feet and three on the hind ones, these later animals showed a similar reduction to their equid kin, so that Palaeotherium, for example, had three toes on each foot, which, together with other features of the limb bones, suggests that it was becoming better suited to running. The diet varied significantly, with some preferring to eat relatively soft foods as their ancestors had done, presumably to extract maximum nutrition, while others were also able to eat tougher food, such as twigs or hard fruit and nuts. The ability to eat abrasive leaves may have helped Plagiolophus to become the only palaeothere to survive the sudden cooling of the climate at the end of the Eocene and survive halfway into the following epoch.

Palaeotherium was, incidentally, the first unambiguous prehistoric mammal to be discovered, all the way back in 1798. This explains the scientific name, which simply means "ancient beast". When George Cuvier formally described it in 1804, he caused something of a stir since he insisted that its existence proved that extinction had to be possible; it had previously been believed that God would never allow such a thing to happen. (Since some people were still unconvinced, this would lead, in the early 19th century, to naturalists making a serious effort to find where all the mastodons were hiding in western North America).

Lophiodon is, like the palaeotheres, a perissodactyl, a member of a group of medium to large herbivores that walk by putting most of their weight on their third toe. Unlike the palaeotheres, however, it is not closely related to any of the modern perissodactyls. It is the best-known member of its family, which, so far as we know, never expanded beyond the islands of western Europe, dying out long before they united with Asia at the end of the Eocene.

In life, it would have been a fairly strange-looking animal, with a comparatively narrow snout and a domed forehead. They were relatively heavily built, with muscular limbs and, like early palaeotheres, four toes on the forefeet and three on the hind ones. They were long considered to be somehow related to tapirs, which at least have a similar body form, but more recent analyses show that they were early relatives of the chalicotheres, large knuckle-walking horse-headed clawed herbivores that would be more prominent in later epochs.

A great many species of Lophiodon are known, with the smallest about the size of a fox, but some were much larger. The biggest, L. lautricense, has been estimated to have weighed possibly as much as two tons, similar to a rhinoceros. Assuming this is true, and the remains are incomplete, so it's difficult to know for sure, it would likely have been the largest land mammal in Europe at the time. Its heavy build makes it unlikely to have been especially fast or graceful, with some analyses suggesting that it may have been partially aquatic, like a hippo. It seems to have browsed on leaves, like the palaeotheres adapting to a tougher diet as time went on. Nonetheless, it and its relatives were apparently unable to adapt fully to the changing climate of the Late Eocene, dying out well before the cold snap that marked its end.

Crivadiatherium is less easily placed. A large-bodied rhinocerous-like animal with a small horn on the snout, it is not a rhino, or even a perissodactyl, but an embrithopod, being related to species that are otherwise mostly known from North Africa and the Middle East. With fossils known only from Romania, it may have crossed over from Turkey to the easternmost islands of the European archipelago and never reached further. It seems to have lived in lakeside environments and may have been a distant relative of elephants.

The subtropical jungles of Eocene Europe were also home to primates. At this early time, none of them belonged to any living families but we can at least say that they were closer to lemurs than to monkeys, although they likely represented one (or more) early side-branches from the line that led to the former.

Europolemur, from Germany, is a typical example. In many respects, including its body size, it resembled a living lemur and had, for example, an opposable thumb and a grooming claw on the hind feet. On the other hand, it lacked the toothcomb that is a primary distinguishing feature of living lemurs and lorises, although the general pattern of the teeth is the same as that of many living primates. Darwinius is another German species and likely a close relative. At the time of its discovery, it was hailed as a possible missing link between the lemur-like and simian primates, but this has been disputed since, and no longer seems to be a common opinion. Whatever it is, an analysis of its gut contents showed that it ate mostly fruit, along with plenty of leaves, but no insects, suggesting a diet similar to that of living lemurs.

The omomyids were much smaller primates, with one of the larger forms, Necrolemur, still weighing only around 200g (7 oz.) They had large eyes, suggesting a nocturnal lifestyle, short faces and long tails and are thought to be related to tarsiers, rather than lemurs. The shape of its hips and ankles suggests that it would have been well adapted for leaping from tree to tree, while its teeth suggest a diet heavy on fruit, although probably supplemented by at least some insects.

But of course, the island jungles of Eocene Europe were not just home to herbivores and insectivores. Many mammals were carnivorous, and they too, belonged to families that are no longer with us today. Next time, I will look at some of them.

[Photo by Frank Vincentz, from Wikimedia Commons.]

Looking for Leaves: the Travel Routines of a Koala

2026-05-30T16:56:11.750+01:00

Animals inevitably have a preference for the particular habitat in which they live. Factors such as climate and the presence of suitable hiding and sleeping places are important, along with the presence of suitable food. While climate is less of a problem, food and shelter may be patchily distributed, with insufficient food in any one place to support the animal for long. The animal may also wish to avoid sheltering in any one place for too long, less predators find it easy to locate, and it also makes sense to travel between different patches of land if you want to find mates.

Thus, it can be important to know not merely which habitats a particular species of animal prefers, but how it moves about within that habitat to use to its best advantage. Does it tend to revisit particular patches of ground, and if so, how often? A herbivore, after all, wouldn't want to head back to a given place before whatever it had eaten there had had a chance to regrow.

Research on this topic has tended to focus on birds, especially those that feed on nectar, to which the rate at which flowers replenish their supply is obviously important. For the same reason, bees have not been neglected either, but there is rather less on mammals. Exceptions include herd animals, such as elk and impala, where we do often see a pattern in their wanderings, driven perhaps by herd-leaders' memory of where, and when, they had last found good food sources.

The koala (Phascolarctos cinereus) is an interesting animal for several reasons. It is the only living species in its family and, while the species itself only dates back to the late Ice Ages, it has been well over 20 million years since its ancestors diverged from those of its closest living relatives (wombats). It also has an unusually restricted diet, eating only eucalyptus leaves, with over 20% of its diet coming from just three species.

Eucalyptus leaves are not especially nutritious, so koalas are always on the look out for those with best nitrogen and sugar content, and the lowest amount of bitter chemicals that evolved to deter herbivores. Then, to conserve energy, they sleep for around 20 hours a day, picking trees that do not have edible leaves and that, so far as possible, keep them apart from other koalas. (No, they aren't very sociable).

While it isn't the first study of its kind, a paper published earlier this year used GPS radio collars to track the movements of 25 koalas living in the Liverpool Plains of New South Wales. This area is mostly agricultural, lying just south of the town of Gunnedah and dotted with smaller villages. Agricultural land is of no use to koalas, but there are many small patches of eucalypt woodland, with the largest about 10 km (6 miles) across. This is exactly the sort of fragmented landscape in which movements between patches of food should be easiest to detect.

It turned out that most of the koalas stuck to a routine, moving on after a set period of days in one place. This was often a 7-day pattern, although some had shorter or longer cycles of activity. In particular, males often moved about every other day, possibly because they were patrolling their territory as well as simply looking for food, making sure no rivals had snuck in while they were away feeding. Although this isn't going to be apparent from GPS positioning, they were probably bellowing at one another from strategic points, something that male koalas do to prove their bulk and masculinity.

In contrast, some females kept to a three-week pattern, perhaps reflecting a more intensive use of the local resources before they felt compelled to move on. Regardless of the length of their routine, however, koalas of boths sexes were more likely to stick to it when the weather was dry. Koalas drink very little, getting almost all of the moisture from the leaves that they eat, so it could be that were targeting the trees with the juiciest leaves at this time, similar to the way that elephants make more regular visits to water holes at the driest times of the year.

However, the patch of woodland they chose to move to seems to have been chosen essentially at random, unlike the more organised activity previously reported in deer and hummingbirds. This was less true of those koalas who only had a few nearby patches to pick from, but it's probably easier to slip into a routine when you don't have many choices and still need to make sure you aren't visiting the same place too often.

This last part may be significant for conservation. The koala is not generally considered an endangered species, with around 300,000 of the furry marsupials being found across much of eastern Australia. However, there is some evidence of population decline, with a 2012 estimate suggesting a fall of 28% over the prior 24 years. That may have changed for the better since, and there were uncertainties in the evidence even then, but climate change is unlikely to be helping, so we don't really know.

If koalas living in edge environments with limited choice of feeding grounds are being forced into stricter routines, the authors of the study conclude, we can make their lives easier by boosting connectivity. This could be done by maintaining the existing patches, restoring some corridors of tree growth along streams, and perhaps even by planting small groups of trees between the larger patches, so that the koalas can roam further and have more feeding and resting places to choose from. And, while this study was conducted outside of the breeding season, that would probably help them find mates, too.

Which has got to be good for them, and would likely benefit other species, too. The koala may be famous for only eating eucalyptus leaves, but the same is true of the southern greater glider (Petauroides volans)... and that really is endangered. If some koalas are getting stuck in a rut, rarer species may be finding it even harder.

[Photo by JJ Harrison, from Wikimedia Commons.]

Euplerids: The Not-Mongooses of Madagascar

2026-05-24T17:04:58.564+01:00

Ring-tailed vontsira

There are around 35 currently recognised species of mongoose, spread between Asia and continental Africa. For the most part, they look fairly similar, with most being instantly identifiable as such. For most of the 20th century, however, they were also thought to live on Madagascar. In the last couple of decades, genetic studies have revealed that the Madgascan species, while related to the mongoose family proper, belong in a group of their own. That's partly because they diverged so far back in time, but also because that group includes some animals that manifestly aren't mongooses.

Today, in order to distinguish what we used to call "Madagascan mongooses" from the real sort, we tend to use the local Malagasy word and describe them as "vontsiras".

By far the most common species, and perhaps the most frequently seen mammalian carnivore on the island, is the ring-tailed vontsira (Galidia elegans). Even so, it remains a relatively unknown animal to the outside world, and, in part due to the relative isolation of Madagascar, has not received much attention from zoologists either. The scientific studies that mention it generally do so in combination with the rest of the carnivoran community on the island, rather than spending their time looking at it specifically. Often, it makes sense to look at the larger picture before we focus on individual species, and we're still trying to do that first part.

They have a similar body shape to some of the more slender mongooses, with short limbs and a bushy tail. They are a similar size, too, being 30-36 cm (12 to 14 inches) in length, plus a tail about two-thirds that again. Their coat colour varies considerably; almost a rich chestnut red seems to be the most common, and the tail is striped. There are at least two subspecies, with one having a paler coat than the other, but whether other variations in coat colour represent distinct populations or just individual variation is less clear.

It inhabits damp tropical jungles, avoiding the drier woodlands of the south, but otherwise seems relatively flexible, which may explain its relative frequency. For example, it often leaves the cover of trees to venture into nearby cleared land and seems tolerant of human activity so long as it isn't actively threatened. Even so, the contraction of forest across much of Madagascar leaves it now largely confined to the eastern coast, although some populations do exist elsewhere. It can be found from coastal woodlands all the way up to the treeline on the mountains at around 1,950 metres (6,400 feet).

It is also a generalist feeder, mostly preying on rodents, birds, and the local insectivores, as well as invertebrates, but able to adapt its diet to whatever is available. For example, it has been observed fishing in streams, probably helped by its forefeet that are partially webbed. One report concerned a pair of vontsiras descending on a mass aggregation of mating toads, killing them in a frenzy that left more dead than they could reasonably consume. They will also eat lemurs, including some much larger than themselves, although it's possible that at least some of these are scavenged from the kills of other animals, such as eagles.

They are most active during the day, but can adjust their behaviour in the presence of competitors, such as dogs and civets that have been introduced to the island. They are mostly solitary, but are sometimes seen in small family groups of up to four, perhaps indicating more social cohesion than is typical for their relatives, the civets.

They are also quite vocal, having been recorded making a range of sounds, including whistles, growls, and screams. One particular high-pitched screech is associated with encountering another member of their own species perceived as dominant, in which case the weaker animal bends its front legs down to press its chest against the ground, raising its head and baring its teeth in a submissive posture. They also communicate through scent markings, having perineal glands similar, but less developed than, those of civets, as well as others on the cheeks and chin, much as cats do.

Although they are capable of climbing trees, they don't spend much time in them, sleeping in rocky crevices and hollows at the base of trunks, or else in burrows that they construct themselves. Their digging skills have also been put to use in extracting rodents trying to escape into their own burrows.

Mating is a noisy but brief affair, although it apparently doesn't involve neck-biting by the male as seen in many similar species. Females give birth to a single young at a time, which is born fully-furred and capable of hearing, but doesn't open its eyes until the fourth day. They are weaned at around two months, and can hunt for themselves at three, but often stay with their parents for up to a year. Rare sightings of family groups of four may indicate that, at least some of the time, females can raise two consecutive children in the same year.

Boky-boky

Over on the western side of the island, we have the boky-boky (Mungotictis decemlineata), also known as the "narrow-striped vontsira" and by variations of those two names. It's similar in body form to its ring-tailed relative, but is slightly smaller at 25 to 30 cm (10 to 12 inches) in body length. The body and tail fur are grey, with ten narrow stripes of darker fur running down the back.

The boky-boky inhabits moderately dry deciduous forest dominated by baobab trees. Such woodlands are more common on this side of the island, sheltered from the monsoon winds of the Indian Ocean. It primarily eats insects and other small invertebrates, which form about 85% of the diet. Many of these are beetle grubs dug from the dead wood of fallen trees or from out of the soil surface. The remaining 15% includes various larger prey, such as rodents and small reptiles. Analyses of their droppings include some larger animals, such as lemurs, but it's likely these are the result of scavenging - which is probably also responsible for the local myth that they kill and eat large constrictor snakes.

Like the ring-tailed species, they are active during the day, although they may be more inclined to climb trees. At night, they will shelter in burrows during the dry season, but more often use tree hollows when the ground becomes too damp at other times of the year. Compared with many similar animals, they are surprisingly sociable, living in groups of up to five individuals, even ignoring any young they may have. The groups are usually single-sex (infants aside), although males may, at least temporarily, sometimes join the female groups. Individual groups are tolerant of one another, rarely resorting to fighting, although the males scent mark places where their territories overlap, and the females just seem to avoid one another.

Unlike the ring-tailed species, they make only a narrow range of sounds, the most common of which has been described as a "bouk-bouk" sound that obviously goes a long way to explaining their Malagasy name. The young are precocious, being able to open their eyes from birth, and teething for the first time at just four days old. Unusually, all the young of a particular all-female group are placed together in a creche burrow, the entrance of which is too narrow for the mother to enter; since they are able to walk almost from birth, they emerge from the creche whenever the mother calls them to feed, and are otherwise well hidden.

The alternative name "narrow-striped vontsira" implies the existence of a broad-striped species and, in fact, there are two. The one that actually carries that name, the broad-striped vontsira (Galidictis fasciata) inhabits much the same area of humid, east-coast forest as the ring-tailed species. However, it is more picky about its habitat and avoids direct competition by being entirely nocturnal, only active when its potential rival is asleep.

It is similar in size to the narrow-striped species, but has a greyish-biege coat marked with broad black stripes running the length of the body. Other than this, very little is known of it, and it's apparently unfamiliar even to many of the locals. Doubtless, a combination of shy habits and it being a nocturnal animal living only in dense woodland contributes to its elusive nature. When it is seen, it's often in pairs, suggesting some sort of family unit, and in other respects, it is assumed to be similar to other vontsiras, if only due to a lack of information to the contrary.

Broad-striped vontsira

Its closest relative is Grandidier's vontsira (Galidictis grandidieri). Only recognised as a distinct species in 1986, it is similar in appearance to the broad-striped species, but is notably larger. Indeed, it is the largest of all the vontsiras, up to 48 cm (19 inches) in length, excluding the tail, and with weights of up to 1.7 kg (3 lbs 8 oz.) having been recorded for the largest males.

(You may note, incidentally, that the scientific name as given in the original paper linked above does not quite match the current one. Although the first name to be given usually stands as is, regardless of what else may happen, in this case the Latin grammar proved to be incorrect... and there's only so much the relevant registering body will put up with).

Unusually, it is not a forest-dweller, being known only from the very driest part of Madgascar, a short stretch of land near the southwest coast. The vegetation here is dominated by scrubby succulent plants vaguely resembling cactuses, which are most abundant along a fault line running through the area where underground aquifers reach close to the surface. It's not known whether Grandidier's vontsira needs to drink water, or whether it gets enough from its food... but that food, which consists mainly of cockroaches and locusts, is itself most common along the fault line. Larger invertebrates, such as scorpions, are also eaten, as are a few vertebrates, although the latter are so much larger than anything else it eats that they may well provide the majority of its caloric intake.

Grandidier's mongoose is nocturnal, sheltering in crevices of the cliff face near the fault line, and presumably in similar places elsewhere. It does not appear to excavate its own burrows, but when so much of the local rock is limestone, it hardly needs to, since natural tunnels of the right size can extend for metres into the rock, helping it shelter from the desert sun. Although they are often seen in pairs, larger groups are much rarer, although this may have as much to do with the lack of widespread resources to feed off as anything else.

One thing we do know is that, since the area it lives in may be as small as 1,500 km² (580 square miles) and its suitable habitat within that area is declining, it undoubtedly qualifies as an endangered species, and it has been recognised as such almost since it was discovered. Nor is it alone, since the boky-boky, while not so concentrated in a single area, lives in forests that are being lost more rapidly than those on the east coast, and has been formally listed as an endangered species since 2015.

The least-known species is the brown-tailed vontsira (Salanoia concolor) which has a relatively drab grizzled brown colour making it look especially mongoose-like. It lives in the humid forests of the northeast, which would make it overlap with both the ring-tailed and broad-striped species. It is active during the day, and mainly eats insect grubs that it picks from tree bark; it is assumed that patterns of behaviour, or fine details of the diet allow it to co-exist with its relatives, but the exact details so far remain elusive. It appears to be reasonably sociable as, on the rare occasions when it is seen at all, it is often in groups of two or three, but that is pretty much the extent of our knowledge.

In 2010, a population living near Lake Alaotra, much further inland than the others, was suggested to form a distinct species on the basis of geographical isolation and some differences in the body form, such as larger teeth. The area is marshy, which would also indicate a different habitat from the main species. Named as Durrell's vontsira (Salanoia durrelli) this has not been widely recognised, partly due to the lack of records, but, assuming it is valid, the population must be very small, and it would probably count as another endangered species.

Together, these form the majority of the native carnivoran species of Madgascar. However, as noted in my previous post, the reason it took so long to recognise the Madagascan carnivorans as all belonging to same family is that the remaining species look rather different, and have never been assumed to be mongooses. Next time, I will be looking at some of them.

[Photos by Jeff Gibbs, "Heinonlein", and Grigory Morozov, from Wikimedia Commons. Cladogram adapted from Yoder et al. 2003.]

Not Leaving Home: Wolves on the Serengeti

2026-05-17T14:46:07.712+01:00

There is a popular belief that wolf packs are led by an "alpha male", a dominant individual who directs the pack and monopolises breeding opportunities through the force of his masculine aggression. It's all-but universal in modern stories about werewolves, and has even crept into the messaging of online influencers, apparently following the reasoning that anything true of wolves must necessarily also be true of humans.

It is, however, simply not true.

Having said which, it used to be a serious scientific theory, derived from behavioural studies on captive wolves conducted in the mid 20th century. Better studies at the end of the century, looking at wolves in their natural habitats and not stressed by close confinement with non-family members in zoo cages, revealed the truth: not only is the dominant female at least as important as the male, but the correct word for that dominant pair isn't "alpha", it's "parents".

That is, the supposed "betas", the males in the pack that aren't breeding, aren't weedy individuals hoping to build themselves up to prove their masculinity by challenging the "alpha male". They're just his children who haven't left home yet. While there certainly are mammalian species in which the male competes for dominance or monopolises mating opportunities through the force of his masculinity (most deer, for example), wolves are not among them.

The actual breeding system is a cooperative, family-based one, based around a monogamous pair. The younger individuals gain the benefit of pack-living, being able to cooperate to take down large prey, in return for which they help look after their younger siblings, taking the strain off their mother.

This likely evolved together with the tendency for wolf mothers to have large litters that might otherwise be too large for them to handle on their own. This puts the dominant female (that is, the pack mother) in the central position when it comes to determining mating opportunities, but, in practice, she's unlikely to be 100% succesful. The degree to which that's down to the sheer practicality of stopping your daughters from doing things you'd rather they didn't, and the degree to which giving older daughters some leeway ensures help with rearing younger pups, is open to debate.

While looking at wolves may be a bad guideline for human behaviour, it is much more likely to be relevant to the behaviour of their own close relatives. Large litters are a feature of many canid species, and it's therefore likely that many of them face the same pressures. Indeed, we find, when we look at the wolf's closest relatives, that, even if their hunting packs aren't usually quite so large, monogamy supported by wider cooperation is the norm among them.

When I'm talking about "wolves" above, the species I am referring to is technically the grey wolf (Canis lupus), the species that dogs were domesticated from, and that is usually referred to simply as a "wolf" in most parts of Eurasia and North America, where they live. In contrast, the African wolf (Canis lupaster) is a different species.

Previously thought to be a jackal, it was only raised to full species level in 2015, when it was split away from the golden jackal (Canis aureus) on genetic grounds. The name comes from the fact that it is more wolf-like than true jackals, and lives only in northern Africa, reaching as far south as Senegal and Kenya. Indeed, genetic evidence suggests that it may have arisen as a result of cross-breeding between grey wolves and another, Ethiopian, species (Canis simensis) in the distant past.

A long-term study of African wolves on the Serengeti, near the southern boundary of their range, began in 1977, and continues to this day. By now, this means that we have a large database of information that we can go back to and examine to see how packs evolve and interact, and how they change with time. One recent analysis looked into family interactions and asked what best contributes to parents raising more pups.

Between 1977 and 1990, the African wolves in the study area gave birth to a total of 36 litters. Just as with grey wolves, monogamous pairs formed the basis of the social structure, with each pair staying together for up to eight years, defending an area of 0.5 to 2 km² (125 to 500 acres). Packs are much smaller than in grey wolves, but, for twelve of the litters, the parents had at least some assistance from another adult wolf, bringing back food for the pups or for the lactating mother. There was usually just the one helper in these cases, although two or even three helpers were sometimes seen.

Having said which, some younger wolves just hung around in the territory without visibly being helpful, although it's possible that they helped defend the territory against rivals. Since they only tended to hang around for a single year, it's likely that they were using their parents' territory as a base from which to explore the surrounding area before striking out on their own.

Although litters typically result in the birth of up to six pups, as is often the case with wild animals, most do not survive until they can forage for themselves at 14 weeks. On average, each mated pair managed to successfully raise 1.17 pups per litter if they had no assistance. Since they will have several litters over the course of a lifetime and, on rare occasions, even two in a year, that's sufficient to maintain the population and grow it over the long term if resources allow.

But it's significant that it takes both parents to do this, and this is probably why African wolves (and most other canids) are monogamous in the first place. If the males each dominated a harem, or mated with several females and then left them to their own devices, the mothers would struggle to raise pups on their own. What works for deer or cats doesn't work for wolves; the father has to stay around and be helpful.

Indeed, there was one instance of a single mother during the study, a younger intruder who had evidently managed to mate with the dominant male, who was then far too busy with his partner's pups to help her with hers. All of her pups died, and so did she.

However, add in another adult wolf not breeding, but being seen to help feed their younger siblings, and things improve. That extra helper meant that, on average, 0.58 pups per litter survived for 14 weeks. Over the lifetime of the mother, that adds up to several more children reaching the age to have children of their own.

The advantage to this for the parents is obvious, but what are the helpers getting out of it? They are putting off leaving to find a partner and raise children of their own, they may risk injury defending territory that isn't really theirs, and they are even putting effort and resources into the task, potentially putting them at unnecessary risk should conditions suddenly get worse.

Well, for one thing, it probably helps that the pups they are assisting are their own siblings, whose survival could benefit their family genes in the long run. They may also receive reciprocal help from the parents when times get hard, and the practice of looking after pups may stand them in good stead when they do eventually leave. Also, by staying where they are, they may get the chance to keep an eye out for openings in neighbouring territories, should a member of an unrelated pair die and leave her partner looking for someone new.

It might, perhaps, be different if such situations occurred regularly. But, at least in the Serengeti during the years of this study, they arose only rarely. The main problem was simply the lack of territory - there was just nowhere for a new pair to set themselves up most of the time. This changed partway through the study when there was a local outbreak of canine parvovirus, reducing the total population. In the following years, young wolves were more likely to establish new territories and find a partner willing to share it with them, but it took a while to rebuild the population, partly because first-time parents don't gain the benefit of older children helping them look after young ones.

However, while African wolves will drive off rivals of the same sex from outside their territories, within their home communities, it's all about cooperation, not conflict.

[Photo by Giles Laurent, from Wikimedia Commons.]

A Brief History of Zokors

2026-05-10T14:11:00.004+01:00

The rodents are the largest group of mammals, in terms of number of species, and they are divided into several families. Some of these are familiar, such as the mice, voles, squirrels, and gophers, but others are much less so, at least to the majority of people in the West. This includes, for example, the zokors.

There are a couple of reasons why zokors are not as well-known as some other rodent groups. For one thing, they only live in northeast Asia, an area that it's fair to say doesn't receive much attention in the Western world. For another, even if you did live there, you wouldn't see them very often, because they are burrowing animals that don't like coming to the surface if they can help it. Rather like moles, you might see the mounds of earth they leave, but not often the animal itself.

How the zokors fit into the wider rodent family tree has undergone significant revision over the last few decades. Back in the 20th century, they were considered a subfamily in the mouse family, but then, far more rodents were in those days than is the case now, the older broad definition of "murid" having been refined. Then, at the dawn of the current century, early molecular studies showed that they weren't mice at all but a kind of hamster. Which was a bit surprising, since, while they look a bit like hamsters superficially, they are are different in almost every other respect.

In 2004, however, a flaw was discovered in the original genetic analysis. Specifically, it turned out that the "zokor" whose genetics had been analysed was, in fact, a Siberian hamster. Reanalysis of an actual zokor showed that it belonged to a different rodent family, the blind mole-rats. Some zoologists have argued since then that they're unique enough to be given their own family, but today, they are generally placed as one of three subfamilies with the blind mole-rat family, technically referred to as the spalacids.

Zokors are moderately large rodents, between about 15 and 25 cm (6 to 10 inches) in length. They burrow through the soil using the claws on the front feet, which is a different method than that employed by the mole-rats, which use their teeth. Like the blind mole-rats, they try to avoid venturing above ground, and they have very small eyes and no external ears. (Blind mole-rats, it should be noted, are not the same thing as the African mole-rats, which include the naked sort). They survive by eating roots and underground seeds, and are thought to be quite common in those areas where they live.

There are six living species of zokor, three belonging to the genus Eospalax, and living in central China, and three others living in parts of Siberia, Mongolia, and Manchuria. These last three are usually placed together in the genus Myospalax, from which the subfamily takes its technical name (Myospalacinae), although one species sometimes gets its own, Siphneus.

But we also know of fossil species and, using these, we can piece together something of the history of the group. It's sometimes the case, when there are a small number of living species, that they represent the last gasp of some group that was once more diverse and perhaps wider spread. But that's not the case with the zokors, which don't ever seem to have spread far beyond their current home, and to have lived much the same specialised lifestyle as they do now.

Blind mole-rats as a whole are thought to be a very early branch within the mouse-like rodents, splitting off before, for example, the hamsters and voles separated from the true mice and their kin. This would place their origin around 20 million years ago, but the oldest known fossils that we can specifically call zokors date back to only 9 million.

These belong to Prosiphneus, which lived during the Late Miocene across much of eastern Siberia and northern China and even reached into southwestern Tibet, close to the border with India This is a much wider range than any living species of the group, but the world was warmer then than it is now, with relatively mild conditions likely persisting across the region before they became split into more isolated pockets around 5 million years ago at the dawn of the Pliocene. This breakup of formerly hospitable terrain may have led to the geographic fragmentation of the family we see today, where each species lives in relatively restricted areas.

This change in the climate would have isolated early zokors into at least two different regions, perhaps divided by the Takla Makan desert and the surrounding Kunlun and Tien Shan mountain ranges. One group, represented by the Pliocene genus Pliosiphneus, remained in China, where it is likely that the very first zokors had appeared a few million years earlier. That died out by the end of the epoch, but one isolated group had survived, most likely after becoming trapped in Mongolia by the changing climate of the surrounding regions, and evolved into the genus Episiphneus. Common during the Ice Ages, it eventually moved back south again, giving rise to the modern Chinese zokors, which include the most well-studied species.

Over on the other side, the Pliocene sees the appearance of Siberosiphneus, initially in the western reaches of Siberia. Indeed, the oldest known species of the genus lived on the banks of what is now the Irtysh River, on the eastern side of the Ural Mountains, and thus about as far west as you can get without leaving Siberia. This new species has several features in common with its presumed ancestor Prosiphneus, indicating that it may represent one of the first members of its lineage, shortly after the split with the Chinese species.

This, or something like it, would have given rise to the modern species living further north. During the Ice Ages, this 'Siberian' lineage spread further afield, perhaps driven by the expansion and retreat of the glaciers. While Siberia itself had relatively little in the way of massive ice sheets, being too dry to accumulate enough snow to form them, the permafrost tundra would have shrunk and returned as the interglacials came and went, and permanently frozen subsoil is obviously not going to be encouraging for an animal that would have had to dig through it and still find enough fleshy plant roots to eat.

So it's at this time that the Siberian zokors would have spread east, leading to the appearance of the two modern species in Mongolia and Manchuria. To back up this pattern of sudden dispersal, we also have fossils that appear all-but indistinguishable from the modern Siberian species discovered on the western side of the Urals - and thus in Europe, not Asia - where they would have lived during the Middle Pleistocene. They probably didn't remain there long, perhaps just during an interglacial, but that they got there at all is surprising for something long assumed to be unique to Asia, especially when there was a mountain range in the way.

[Photo by "Avustfel", from Wikimedia Commons.]

Strange Carnivores of Madagascar

2026-05-03T11:40:00.000+01:00

Madagascar is the fourth-largest island in the world, almost three times the size of Great Britain, or half again the size of California. We should not be surprised, therefore, that it has a considerable amount of native wildlife. However, it's also noteworthy that it has been an island for a very long time - certainly for far longer than Britain has been.

In fact, Madagascar became an island around 91 million years ago, over 20 million years before even the likes of Tyrannosaurus appeared on the scene. Moreover, this was when it split away from what was then the island of India, with its break from Africa being almost twice as far back in time. But, even if we take that younger date for the beginning of its isolation from any sort of 'mainland', it's well before any of the sort of mammals we would recognise today had evolved. There's no equivalent here of mammoths nipping across the English Channel.

Yet Madagascar is not devoid of native mammals. Obviously, island isolation doesn't cause any problems for marine mammals that might be found off the coast, and it's not much of a problem for bats, either. But there is far more than this, animals that have somehow made the trip from elsewhere to this large and (at the time) empty land, probably by clinging to some stormswept piece of driftwood. It seems remarkable, but you've got a very, very long time to get it right, and you only need to do it once for any given group of animals.

Lemurs are probably the most famous example of this, but Madagascar also has rodents, small insectivorous mammals, and even carnivores. This last group, however, have posed a significant puzzle to biologists struggling to fit them into the wider carnivoran family tree. It's been known since the early 19th century that, due to the structure of their ear, they are all more related to the "cat" side of the order than to the "dog" one... but it's less obvious how they are related to each other, or to anything on the mainland.

The first species were formally described in the 18th century, before the concept of animal "families" had been developed. They were both placed in the genus Viverra, along with other small, bitey, vaguely cat-like animals, such as the civets I have been looking at recently. But, as more species were named, it became clear that they really appeared quite different from one another and, in some cases, from pretty much anything else.

For around 150 years, different naturalists and taxonomists came up with different schemes, placing some species in one group and others elsewhere, or just throwing up their hands and leaving the weirder ones on their own. Some were placed with the civets, some with the mongooses, and one was regularly classified as a cat, albeit one thought to have branched off from all other cats very early on.

At the heart of this, at least once evolution had become widely accepted, was just how many times new species of carnivorous mammals had reached Madagascar from elsewhere. It's something that, strictly speaking, only needs to have happened once... but that doesn't mean it did, not if their descendants are so obviously different from one another. A lack of fossils on the island, which has few deposits of the right age, didn't help matters.

In 1945, George Gaylord Simpson published an influential classification of mammals that, among many other things, answered this question: it had happened three times. The Madagascan carnivores belonged to three different groups that had, over the course of millions of years, each arrived separately on the island. Of the seven species known at the time, four were mongooses, two were palm civets, and the other one was a viverrid, but odd enough to be given its own subfamily. Aside from debates about whether mongooses were distinct enough to be given a family separate from that of the viverrids, this scheme was followed for the remainder of the century.

It was, as we now know from molecular and genetic studies, wrong.

In 2003, a genetic analysis compared the Madagascan carnivorans with each other and with similar animals elsewhere. As has been confirmed several times since, it turned out that all of the species really did share a single common ancestor that had somehow crossed over from Africa. There had only been one event, and all those features that had confused earlier researchers were down to a mix of rapid adaptation to new niches and cases of parallel evolution.

We now know that the closest relatives of these animals are, in fact, the mongooses, but the split is so far back (about 19 million years ago) that we can't reasonably place them in the same family. Not only that, but the Madagascan carnivores turn out to be more closely related to hyenas than to what had been the other prime contender, the palm civets. An old name for the group was dredged up from a 19th-century classification and raised to family level.

The Madagascan carnivores now had their own family: the Eupleridae.

Given all of this, it should not be surprising that it's impossible to describe what a "typical euplerid" looks like - there is no such thing. With every other carnivoran family, we could reel off a list of features that define them, even if there might be a few species here and there that don't quite fit the usual pattern. But, here we can't; Simpson may have been wrong about them belonging to three different groups, but it isn't as if he didn't have his reasons. That's what it looks like, with some closely resembling mongooses, some civets, and some... not.

There are, in fact, only two unique features that we can say unite the euplerids: they all descend from a single common ancestor, and they all live on Madagascar, and nowhere else. And that's it, which is unusual, especially when you can't even tell the first one is true without conducting genetic analysis.

Of course, there are some features that they have in common; they're just not unique. For instance, the structure of the bones around the ear does follow the "cat-like" pattern seen in their relatives, which at least tells us which half of the carnivoran family tree they belong to.

We can also make generalisations about their teeth; each half of each jaw has three incisors, a canine tooth, three or four premolars and one or two molar teeth. This is very similar to the pattern in mongooses, but the actual shape of the teeth varies remarkably between species, so this isn't really telling us very much beyond the fact that they are suited for a broadly carnivorous diet.

They are all forest-dwelling animals, because that wasn't really anything else to live in before the arrival of humans sometime between the third and sixth centuries AD. Since then, many of the old forests have been cut down to make way for farmland, especially in the central highlands, with the result that euplerids are no longer found through much of the interior. However, the forests that do survive are still reasonably extensive, and vary more than one might think, due to the differing weather patterns on the east and west coasts. The various species, therefore, each have their own preferences for forest type.

The euplerid family is comparatively small, with, depending on who you're asking, anything from eight to ten species. Which, to be fair, is the same as the number of living bear species and is not spread across half the globe as they are, but still. It is divided into two subfamilies, one of which itself contains unusually varied forms.

The other contains those that were long considered to be mongooses. While we now know that isn't what they really are (although, admittedly, they are closer to them than to any other non-euplerid), they are still regularly referred to as such. There has, however, been a trend in recent years to use a new word for them, taken from the native Malagasy language: "vontsira".

Next time, I will be taking a look at them.

[Photo by Rob Foster, from Wikimedia Commons.]

Covid and the Landscape of Fear

2026-04-26T13:22:00.000+01:00

Left to their own devices, animals will wander about wherever there is food or other useful resources to be found. They would be limited only by the physical properties of their landscape, such as the inability to cross a wide river or the presence of a barren mountain range. Reality, of course, is never quite this simple.

The earliest use of the term "landscape of fear" that I could find on a quick search referred to a study about how female college students felt while walking particular routes alone after dark. Put in this context, one can well understand why people don't necessarily pick the simplest or most direct route to their objective, and why there are certain places one might simply wish to avoid altogether.

The idea, however, was soon extended to ecology, whereby the distribution of animals across a landscape is determined, not just by physical factors or the direct action of predators, but by fear. The idea is that particular prey animals might become less common in a particular area, not because predators are killing them in those areas, but because they fear that they might.

So, depending on how the predator you are most concerned about hunts, you might avoid open areas where you can easily be seen, or denser ones where they can easily hide. Puma/cougar/mountain lions, for instance, kill most of their prey near forest edges, and animals such as elk adjust their own movements accordingly. At the very least, prey animals will approach such areas cautiously, remaining vigilant, and thus spending less time feeding or resting than they might elsewhere.

While the general idea had been around for decades, it became extended to the modern biological concept of the "landscape of fear" around 2010, where perceived predation risk, as indicated by any of various measures, is plotted against the physical geography of an area. When we are studying how animals use particular habitats, we need to take fear into account just as much as the availability of useful resources.

But we can extend the concept further. The landscape in question need not be physical; it could also be temporal. Consider those college students again. They might avoid certain places, or be sure to travel in groups or with other protection if they have to (i.e. remaining vigilant), but they might also, so far as possible, just not walk the streets after dark.

This, in the technical parlance of ethology, is "diel behaviour". That is, how your activity changes throughout the day. For example, what is considered the founding study to use the landscape of fear concept showed how elk in Yellowstone Park avoid certain areas because they are afraid of wolves. The assumption was that the elk just found those areas scary, as well they might, and so stayed away from them. But it turns out that elk are quite happy to forage for food in places frequented by wolves if they think that the wolves are asleep.

The landscape of fear can therefore be said to change, not just slowly as habitats change with rivers drying up or whatever, but from hour to hour throughout the day. There are places you might be happy to visit during the day that you wouldn't want to go at night.

Perhaps the clearest example of this comes not from fear of predation, but fear of humans. Even where wild animals are not at direct risk of being hunted by humans, they tend to avoid us, and that's just as much a landscape of fear as anything caused by regular predators. The details can be complex, but a common trend is that animals that have to live near humans become more nocturnal.

That's the opposite of what we would usually do if we found a particular place threatening, but that's rather the point. Humans are mostly active during the day, so if you want to avoid them, then, so far as you possibly can, it is better to be active at night. This is something seen across a wide range of animal species, although the details naturally vary.

But, if the landscape of fear changes over the course of a mere day, how long does it take animals to adjust to changes in human activity? Animals are, after all, capable of learning and, while it would likely depend on the animal species in question, we can easily imagine them becoming more or less wary as the human activity around them waxes and wanes. For instance, a study at a recreation area in Utah showed that mule deer and raccoons are less active at weekends, especially near camping grounds.

If we're talking about changes in human activity levels, however, it's hard to argue that the largest disruption to daily life in modern times was anything other than the COVID pandemic. It's well known that many animals changed their behaviour once they realised that humans were not travelling about so much, and some scientific studies have attempted to quantify that.

One, for example, found that stone martens in Poland were more active in the early evenings during lockdown than they normally would be. Stone martens are nocturnal anyway, so would have had little motivation to exploit quieter days, but they could make use of more of the night if humans weren't around after dark in the evening.

Such studies continue to come out, such is the time taken to conclude data analysis, write everything up formally, and get it published and available. Most tend to focus on either urban areas, where we might expect the effect to be greatest, or recreational areas, where animal monitoring equipment may already be set up and that should have been almost totally deserted during lockdown. One new one, however, looked at the more complex matter of the interface between the two.

This study concerned the Jasper Ridge Biological Preserve operated by Stanford University in the San Francisco Bay Area. It's a 1,193 acre (4.8 km²) preserve described as an "outdoor classroom" for nature studies and education, lying on the traditional land of the Muwekma Ohlone tribe, and thus also referred to by the native name of 'Ootchamin 'Ooyakma. Crucially, it is almost entirely surrounded by suburban housing, close to the university. However, in addition to being a wild area in itself (there are cougars and rattlesnakes, for example), there is a narrow corridor linking it to the nearby wilderness of the Santa Cruz mountains. All of which gives it a different character from a typical city park.

On the 12th March 2020, all of the usual guided tours to the Preserve were cancelled, and four days later, so were all educational and research visits, with access restricted only to essential personnel. Educational services resumed in spring 2021, meaning that the former daily visits were paused for an entire year. Camera traps placed to monitor the activity of the local wildlife, however, remained running throughout.

In fact, they found relatively little effect. Of the six mammal species they were able to evaluate, only brush rabbits (Sylvilagus bachmani) - a type of cottontail found only along the West Coast - changed their behaviour to become notably more active during the day. Jackrabbits shifted the peak of their activity to be less active in the evening after the lockdown ended than they had been during it, but since they were already active then before it started, they don't seem to have noticed the beginning of the period, only its end.

The other four species studied, foxes, bobcats, cougars, and black-tailed deer, changed their activity little or not at all.

The researchers conclude that this may be because the animals in this particular area were already used to human activity, and moreover, human activity that didn't involve hunting and killing them. That is, they already felt secure moving about whenever they wished, and the fact that the humans that hadn't been bothering them in the first place weren't there any more didn't make much difference to them.

They also speculate that the brush rabbits being different had little to do with human activity. They are, of course, relatively small herbivores and had a great deal to fear from the foxes and bobcats. And, while those species were no more active during the day than they had been before, they were actually more active during their usual hunting times at night - perhaps feeling more confident in entering the area in general, rather than at particular times of day. And, with more predators around at night, it made sense for the brush rabbits to stay hidden then and cut back on their nocturnal forays.

But otherwise... well, it seems that there is more than one way to cut back on the landscape of fear.

[Photo by Eric Kilby, from Wikimedia Commons.]