Paleobiology Blog

Enormous volcanic eruptions 16 million years ago

2017-10-12T07:30:00.001-07:00

Washington State University researchers have determined that the Pacific Northwest was home to one of the Earth's largest known volcanic eruptions, a millennia-long spewing of sulfuric gas that blocked out the sun and cooled the planet.

Only two other eruptions -- the basalt floods of the Siberian Traps (251 Ma) and the Deccan Traps (66 Ma) -- were larger, and they led to two of the Earth's great extinctions.

"This would have been devastating regionally because of the acid-rain effect from the eruptions," said John Wolff, a professor in the WSU School of the Environment. "It did have a global effect on temperatures, but not drastic enough to start killing things, or it did not kill enough of them to affect the fossil record."

The research, which was funded by the National Science Foundation, appears in Geology, the top journal in the field. Starting 16.5 million years ago, they say, vents in southeast Washington and northeast Oregon put out a series of flows that reached nearly to Canada and all the way to the Pacific Ocean. The flows created the Wapshilla Ridge Member of the Grande Ronde Basalt, a kilometer-thick block familiar to travelers in the Columbia Gorge and most of Eastern Washington. The researchers say it is "the largest mapped flood basalt unit on Earth."

The researchers estimate that, over tens of thousands of years, the floods put out between 242 and 305 billion tons of sulfur dioxide. That's more than 4,000 times the output of the 1815 Mount Tambora eruption in present-day Indonesia. That eruption blanketed the Earth in an aerosol veil, creating the "Year Without A Summer" and food shortages across the northern hemisphere.

The volume of gas emitted from the Wapshilla Ridge lavas, said the researchers, "is equivalent to a Tambora eruption every day for 11 to 16 years."

Most of the lava's gases were released during the eruptions, but some of the gas remained trapped in crystals near the volcanic vents. Klarissa Davis, lead author of the paper, analyzed the gases as part of her doctoral studies. The other authors are Michael Rowe, now at the University of Auckland, and Owen Neill, now at the University of Michigan.

Wolff puts the eruption into one of three classes of cataclysms, the other two being a caldera eruption like the Yellowstone volcano and the impact of an asteroid. A similar eruption today "would devastate modern society globally," said Wolff.

The eruption also provides an insight into the workings of climate change. It took place in what is known as the Miocene Climactic Optimum, or MCO, when some 50 million years of cooling was interrupted by 5 to 6 degrees Fahrenheit of warming. But at its peak, the MCO had a brief cooling period that coincides with the Wapshilla eruption and its profusion of sulfur dioxide.

Sulfur dioxide is now bandied about as a possible tool for engineering a break in the Earth's current warming trend, though Wolff is not particularly keen on the idea.

"I personally think that it's probably a dangerous thing to do without understanding all of the possible consequences," he said. "But maybe we're getting an idea of some possible consequences here."

Oldest known evidence of life on earth

2017-09-28T08:07:00.004-07:00

Rocks from northern Labrador have been found to contain the oldest known evidence of life on Earth. Graphite found in the Eoarchean rocks (3.95-billion-year-old) shows the geochemical signature of having come from the decomposition of living organisms, researchers report in a study published in Nature.

That's at least 150 million years older than the oldest graphite from living organisms previously found in 3.7 billion to 3.8 billion-year-old rocks in Greenland and northern Quebec, and only about 500 million years after the Earth formed (4.5 billion years ago).

Some of the signatures in the Labrador rocks suggests that the organisms that left them were autotrophic, but not necessary photosynthetic: these organisms could produce their own food from chemicals in their environment, but possibly without light (chemosynthesis).

This discovery suggests that there may have been life during this time, and possibly even abundant life to get carbon-rich sediments. It adds to evidence that the Eoarchean Earth had conditions to support life: surface water and hospitable temperatures.

Researchers have interested in the rocks of the Uivak Gneiss in the Saglek Block of northern Labrador because they contain some of the oldest rocks on the surface of the Earth. Such old rocks are very rare because the Earth's crust is constantly being recycled back into the planet's interior through a process called plate tectonics. The Labrador rocks are likely a small patch that remains from a very ancient continent.

Because such rocks are so rare, very little is known about the Earth at that time, although it's known that the interior of the Earth was much hotter than it is now, and there is some evidence of liquid water on the surface. It is uncertain whether there were ponds or oceans at this time on Earth.

What makes the Labrador rocks particularly special is that they are the oldest known rocks that are "metasedimentary": rocks formed from sediments deposited by water. The "meta" part of the word indicates that the rocks have been "metamorphosed" or transformed by heat and pressure over time.

Graphite, the same substance found in pencils, can be formed from chemical reactions of inorganic materials., but it can also be formed when decaying organic matter gets heated up to several hundred degrees. Scientists can tell the difference by looking at the type of carbon found in the graphite. Carbon atoms come in different "isotopes" or forms with different masses: Carbon-12, Carbon-13 and Carbon-14. Carbon-12 is the most common, and the kind that organisms tend to disproportionately take into their bodies. That means graphite that comes from living things tends to be lighter than graphite from inorganic sources.

To figure out whether graphite came from a living or non-living source, researchers use instruments to compare the ratio of Carbon-12 to Carbon-13. This research can be complicated by contamination over millions of years, or when the graphite has been exposed to heat and pressure, which can change the carbon ratios.

These researchers tested for contamination, accounted for the exposure to heat and pressure, and extrapolated the original ratios of 12C to 13C. The carbon signature can indicate whether the graphite came from living organisms, as well as the type of metabolism of those organisms.

The researchers indicate that the ratio found in one sample provides the oldest evidence for autotrophs, in which ancient organisms used a metabolic pathway similar to modern microbes that turn carbon dioxide into methane and acetate.

Tashiro, T., A. Ishida, M. Hori, M. Igisu, M. Koike, P. Méjean, N. Takahata, Y. Sano, and T. Komiya. 2017. Early trace of life from 3.95 Ga sedimentary rocks in Labrador, Canada. Nature 549: 516-518.

Eutrophication and the rise of animals

2017-08-17T09:34:00.001-07:00

Researchers at the Australian National University (ANU) have provided new evidence for the catalyst on how the first animals appeared on Earth. The team found the evidence in ancient sedimentary rocks from central Australia that indicated a transition from a bacteria-dominated environment to an algae-dominated environment around 650 million years ago, during the Cryogenian period. The causes and geological timing of this transition, as well as possible links with rising atmospheric oxygen levels and the evolution of animals, remained obscure.

The molecular fossil record demonstrates that bacteria were the only notable photosynthetic organisms in the oceans before the Cryogenian. There was a sharp increase in the molecular diversity and abundance due to the the rapid rise of marine planktonic algae between 659–645 million years ago.

What caused this abrupt change?

Around 700 million years ago, there was a world-wide glaciation event, called "Snowball Earth event", in which the Earth's temperatures plummeted, such that entire oceans were completely or partially frozen-over. Glaciers on land, similar to today, moved with great pressure and force that ground entire mountain ranges into smaller particles or till, releasing the minerals in these rocks.

This event was followed by an extreme global heating, when carbon dioxide levels rose. The melting glaciers carried these minerals into rivers and then oceans. Extremely high levels of nutrients in the ocean, and cooling of global temperatures to more hospitable levels, created the perfect conditions for the rapid spread of algae. It allowed for a transition from oceans being dominated by bacteria to a world inhabited by more complex life.

Algae were large and nutritious organisms at the base of the food web, providing a burst of energy required for the evolution of complex ecosystems, where increasingly large and complex animals could thrive on Earth. The ‘Rise of Algae’ created food webs with more efficient nutrient and energy transfers, driving ecosystems towards larger and increasingly complex organisms.

Brocks, J.J., A.J.M. Jarrett, E. Sirantoine, C. Hallmann, Y. Hoshino, and T. Liyanage. 2017. The rise of algae in Cryogenian oceans and the emergence of animals. Nature.

World’s oldest fossils unearthed

2017-03-04T11:52:00.002-08:00

Remains of microorganisms at least 3,770 million years old have been discovered by an international team led by UCL scientists, providing direct evidence of one of the oldest life forms on Earth.

Tiny filaments and tubes formed by bacteria that lived on iron were found encased in quartz layers in the Nuvvuagittuq Supracrustal Belt (NSB), Quebec, Canada.

The NSB contains some of the oldest sedimentary rocks known on Earth which likely formed part of an iron-rich deep-sea hydrothermal vent system that provided a habitat for Earth’s first life forms between 3,770 and 4,300 million years ago.

“Our discovery supports the idea that life emerged from hot, seafloor vents shortly after planet Earth formed. This speedy appearance of life on Earth fits with other evidence of recently discovered 3,700 million year old sedimentary mounds that were shaped by microorganisms,” explained first author, PhD student Matthew Dodd (UCL Earth Sciences and the London Centre for Nanotechnology).

Published today in Nature and funded by UCL, NASA, Carnegie of Canada and the UK Engineering and Physical Sciences Research Council, the study describes the discovery and the detailed analysis of the remains undertaken by the team from UCL, the Geological Survey of Norway, US Geological Survey, the University of Western Australia, the University of Ottawa and the University of Leeds.

Prior to this discovery, the oldest microfossils reported were found in Western Australia and dated at 3,460 million years old but some scientists think they might be non-biological artefacts in the rocks. It was therefore a priority for the UCL-led team to determine whether the remains from Canada had biological origins.

The researchers systematically looked at the ways the tubes and filaments, made of haematite – a form of iron oxide or ‘rust’ – could have been made through non-biological methods such as temperature and pressure changes in the rock during burial of the sediments, but found all of the possibilities unlikely.

The haematite structures have the same characteristic branching of iron-oxidising bacteria found near other hydrothermal vents today and were found alongside graphite and minerals like apatite and carbonate which are found in biological matter including bones and teeth and are frequently associated with fossils.

They also found that the mineralised fossils are associated with spheroidal structures that usually contain fossils in younger rocks, suggesting that the haematite most likely formed when bacteria that oxidised iron for energy were fossilised in the rock.

“We found the filaments and tubes inside centimetre-sized structures called concretions or nodules, as well as other tiny spheroidal structures, called rosettes and granules, all of which we think are the products of putrefaction. They are mineralogically identical to those in younger rocks from Norway, the Great Lakes area of North America and Western Australia,” explained study lead, Dr Dominic Papineau (UCL Earth Sciences and the London Centre for Nanotechnology).

“The structures are composed of the minerals expected to form from putrefaction, and have been well documented throughout the geological record, from the beginning until today. The fact we unearthed them from one of the oldest known rock formations, suggests we’ve found direct evidence of one of Earth’s oldest life forms. This discovery helps us piece together the history of our planet and the remarkable life on it, and will help to identify traces of life elsewhere in the universe.”

Matthew Dodd concluded, “These discoveries demonstrate life developed on Earth at a time when Mars and Earth had liquid water at their surfaces, posing exciting questions for extra-terrestrial life. Therefore, we expect to find evidence for past life on Mars 4,000 million years ago, or if not, Earth may have been a special exception.”

- See more at: http://www.ucl.ac.uk/news/news-articles/0217/010317-Worlds-oldest-fossils-unearthed/#sthash.JrPen2BZ.dpuf

A Fertilizer Dearth Foiled Animal Evolution for Eons?

2017-01-08T10:24:00.001-08:00

For three billion years or more, the evolution of the first animal life on Earth was ready to happen, practically waiting in the wings. But the breathable oxygen it likely required wasn’t there, and a lack of simple nutrients may have been to blame.

Then came a fierce planetary metamorphosis. Roughly 800 million years ago, in the late Proterozoic Eon, phosphorus, a chemical element essential to all life, began to accumulate in shallow ocean zones near coastlines widely considered to be the birthplace of animals and other complex organisms, according to a new study by geoscientists from the Georgia Institute of Technology and Yale University.

Along with phosphorus accumulation came an oceanic chemical chain reaction, which included other nutrients, that powered organisms to pump oxygen into the atmosphere and waters. Shortly after that transition, which in geohistorical terms can mean about 100 million years, waves of climate extremes swept the globe, freezing it over twice for tens of millions of years each time, a highly regarded theory holds.

The elevated availability of nutrients and bolstered oxygen also likely fueled evolution’s greatest lunge forward.

After billions of years, during which life consisted almost entirely of single-celled organisms, animals evolved. At first, they were extremely simple, resembling today’s sponges or jellyfish, but Earth was on its way from being, for eons, a planet less than hospitable to complex life to one bursting with it.

Earth’s true genesis
In the last few hundred million years, biodiversity has blossomed, leading to dense jungles and grasslands echoing with animal calls, and waters writhing with every shape of fin and color of scale. And most every stage of development has left its mark on the fossil record.

The researchers are careful not to imply that phosphorous necessarily caused the chain reaction, but in sedimentary rock taken from coastal areas, the nutrient has marked the spot where that burst of life and climate change took off. “The timing is definitely conspicuous,” said Chris Reinhard, an assistant professor in Georgia Tech’s School of Earth and Atmospheric Sciences.

Reinhard and Noah Planavsky, a geochemist from Yale University, who headed up the research together, have mined records of sedimentary rock that formed in ancient coastal zones, going down layer by layer to 3.5 billion years ago, to compute how the cycle of the essential fertilizer phosphorus evolved and how it appeared to play a big part in a veritable genesis.

They noticed a remarkable congruency as they moved upward through the layers of shale into the time period where animal life began, in the late Proterozoic Eon.

“The most basic change was from very limited phosphorous availability to much higher phosphorus availability in surface waters of the ocean,” Reinhard said. “And the transition seemed to occur right around the time that there were very large changes in ocean-atmosphere oxygen levels and just before the emergence of animals.”

Phosphorus at the beach
Reinhard and Planavsky, together with an international team, have proposed that a scavenging of nutrients in an anoxic (nearly O2-free) world stunted photosynthetic organisms that otherwise had been poised for at least two billion years to make stockpiles of oxygen. Then that balanced system was upset and oceanic phosphorus made its way to coastal waters.

The scientists published their findings in the journal Nature on Wednesday, December 21, 2016. Their research was funded by the National Science Foundation, the NASA Astrobiology Institute, the Sloan Foundation and the Japan Society for the Promotion of Science.

The work provides a new view into what factors allowed life to reshape Earth’s atmosphere. It helps lay a foundation that scientists can apply to make predictions about what would allow life to alter exoplanets' atmospheres, and may inspire deeper studies, here on Earth, of how oceanic-atmospheric chemistry drives climate instability and influences the rise and fall of life through the ages.

Cyanobacteria, the mother of O2
Complex living things, including animals, usually have an immense metabolism and require ample O2 to drive it. The evolution of animals is unthinkable without it.

The path to understanding how a nutrient dearth would starve out breathable oxygen production leads back to a very special kind of bacteria called cyanobacteria, the mother of oxygen on Earth.

“The only reason we have a well-oxygenated planet we can live on is because of oxygenic photosynthesis,” Planavsky said. “O2 is the waste product of photosynthesizing cells, like cyanobacteria, combining CO2 and water to build sugars.”

And photosynthesis is an evolutionary singularity, meaning it only evolved once in Earth’s history – in cyanobacteria.

Some other biological phenomena evolved repeatedly in dozens or hundreds of unrelated incidences across the ages, such as the transition from single-celled organisms to rudimentary multicellular organisms. But scientists are confident that oxygenic photosynthesis evolved only this one time in Earth’s history, only in cyanobacteria, and all plants and other beings on Earth that photosynthesize co-opted the development.

The iron anchor
Cyanobacteria are credited with filling Earth’s atmosphere with O2, and they’ve been around for 2.5 billion years or more.

That begs the question: What took so long? Basic nutrients that fed the bacteria weren’t readily available, the scientist hypothesize. The phosphorus, which Planavsky and Reinhard specifically tracked, was in the ocean for billions of years, too, but it was tied up in the wrong places.

For eons, the mineral iron, which once saturated oceans, likely bonded with phosphorous, and sank it down to dark ocean depths, far away from those shallows -- also called continental margins -- where cyanobacteria would have needed it to thrive and make oxygen. Even today, iron is used to treat waters polluted with fertilizer to remove phosphorous by sinking it as deep sediment.

The researchers also used a geochemical model to show how a global system with high iron concentration and low phosphorus availability combined with low nitrogen availability in ocean shallows could perpetuate itself in a low-oxygen world.

“It looks to have been such a stable planetary system,” Reinhard said. “But it’s obviously not the planet we live on now, so the question is, how did we transition from this low-oxygen state to where we are now?”

What ultimately caused that change is a question for future research.

Phosphorus starting pistol
But something did change about 800 million years ago, and cyanobacteria and other minute organisms in continental margin ecosystems got more phosphorus, the backbone of DNA and RNA, and a main actor in cell metabolism. The bacteria became more active, reproduced more quickly, ate lots more phosphorus and made loads more O2.

“Phosphorus is not only essential for life,” Planavsky said. “What’s implicit in all this is: It can control the amount of life on our planet.”

When the newly multiplied bacteria died, they fell to the floor of those ocean shallows, stacking up layer by layer to decay and enrich the mud with phosphorus. The mud eventually compressed to stone.

“As the biomass increased in phosphorus content, the more of it landed in layers of sedimentary rock,” Reinhard said. “To scientists, that shale is the pages of the sea floor’s history book.”

Scientists have thumbed through them for decades, compiling data. Planavsky and Reinhard analyzed some 15,000 rock records for their study.

“The first compilation we had of this was only 600 samples,” Planavsky said. Reinhard added, “But you could already see it then. The phosphorus jolt was as clear as day. And as the database grew in size, the phenomenon became more entrenched.”

That first signal of phosphorus in Earth’s coast shallows pops up in the shale record like a shot from a starting pistol in the race for abundant life.

The following people coauthored the study: Benjamin Gill from Virginia Tech, Kazumi Ozaki from the University of Tokyo, Leslie Robbins and Kurt Konhauser from the University of Alberta, Timothy Lyons from the University of California Riverside, Woodward Fischer from the California Institute of Technology, Chunjiang Wang from the University of Petroleum in Beijing, and Devon Cole from Yale University. The study was funded by the National Science Foundation (grant EAR-1338290), the NASA Astrobiology Institute (grant NNA15BB03A), the Sloan Foundation (grant FR-2015-65744), and the Japan Society for the Promotion of Science. Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the sponsoring agencies.

Life on Land started earlier than assumed

2016-11-19T11:48:00.002-08:00

Life on land may have begun much earlier than anyone thought.

"Life was not only present but thriving in soils of the early Earth about two thirds of the way back to its formation from the solar nebula," according to the UO's Greg Retallack, a professor in the Department of Earth Sciences and director of paleontology collections at the Museum of Natural and Cultural History.

Retallack's UO team says that soils were alive long before trees or lichens evolved. The evidence comes from a microscopic study of soils from 3 billion year old rocks found in ancient landscapes near Mount Grant in Western Australia and is detailed in December's international journal Gondwana Research.

Retallack's team focused on microfossils in the rocks using equipment at the UO's Center for Advanced Materials Characterization of Oregon.

The tiny fossils require a microscope to see and probably represent whole organisms, Retallack said. The rocks had long been thought to be of marine origin; however, "a closer look at the dusty salt minerals of the rocks suggests they had to have experienced evaporation on land," he said.

Other mineral and chemical tracers found in the rocks also required weathering in soils of the distant geological past, he said.

The study considered at least five different kinds of microfossils recognized from their size, shape and isotopic compositions.

The largest and most distinctive microfossils are spindle-shaped hollow structures of a mold-like bacteria — a mostly land-based group of decomposers that are responsible for the characteristic earthy smell of garden soil. Other sphere-shaped fossils are similar to purple sulfur bacteria, which photosynthesize organic compounds in the absence of oxygen while leaving abundant sulfate minerals in the soil.

“With cell densities of over 1,000 per square millimeter and a diversity of producers and consumers, these microfossils represent a functioning terrestrial ecosystem, not just a few stray cells," Retallack said. “They are evidence that life in soils was critical to the cycles of carbon, phosphorus, sulfur and nitrogen very early in the history of the planet.”

The findings are likely to keep stirring debate. In a 2012 paper in the journal Nature, Retallack drew criticism when he argued that the ancient fossils are a primitive precursor to lichen or fungi and that helped colonize land.

Scientists have long pointed to stromatolites, a life form that emerged 3.7 billion years ago, and other ocean life as evidence that living organisms evolved in the sea and migrated into intertidal rock formations.

The ancient soils from Australia's Pilbara region, Retallack said, are similar to those found recently by the Mars rover Curiosity. "They may," he said, "be useful as guides for the discovery of life on other planets."

Retallack, G.J., D.H. Krinsley, R. Fischer, J.J. Razink, and K.A. Langworthy. 2016. Archean coastal-plain paleosols and life on land. Gondwana Research 40: 1-20.

For ancient deep-sea plankton, a long decline before extinction

2016-07-22T10:41:00.001-07:00

A new study of nearly 22,000 fossils finds that ancient plankton communities began changing in important ways as much as 400,000 years before massive die-offs ensued during the first of Earth’s five great extinctions.

The research, published July 18 in the Early Edition of the Proceedings of the National Academy of Sciences, focused on large zooplankton called graptolites. It suggests that the effects of environmental degradation can be subtle until they reach a tipping point, at which dramatic declines in population begin.

“In looking at these organisms, what we saw was a disruption of community structures — the way in which the plankton were organized in the water column. Communities came to be less complex and dominated by fewer species well before the massive extinction itself,” says co-author H. David Sheets, PhD, professor of physics at Canisius College and associate research professor in the Evolution, Ecology and Behavior graduate program at the University at Buffalo.

This turmoil, occurring in a time of ancient climate change, could hold lessons for the modern world, says co-author Charles E. Mitchell, PhD, professor of geology in the University at Buffalo College of Arts and Sciences.

The shifts took place at the end of the Ordovician Period some 450 million years ago as the planet transitioned from a warm era into a cooler one, leading eventually to glaciation and lower sea levels.

“Our research suggests that ecosystems often respond in stepwise and mostly predictable ways to changes in the physical environment — until they can’t. Then we see much larger, more abrupt, and ecologically disruptive changes,” Mitchell says. “The nature of such tipping point effects are hard to foresee and, at least in this case, they led to large and permanent changes in the composition of the oceans' living communities.

“I think we need to be quite concerned about where our current ocean communities may be headed or we may find ourselves at the tail end of a similar event — a sixth mass extinction, living in a very different world than we would like.”

The study was a partnership between Canisius, UB, St. Francis Xavier University, Dalhousie University and The Czech Academy of Sciences.

A long slide toward oblivion

In considering mass extinction, there is perhaps the temptation to think of such events as rapid and sudden: At one moment in history, various species are present, and the next they are not.

This might be the conclusion you’d draw if you examined only whether different species of graptolites were present in the fossil record in the years immediately preceding and following the Ordovician extinction.

“If you just looked at whether they were present — if they were there or not — they were there right up to the brink of the extinction,” Sheets says. “But in reality, these communities had begun declining quite a while before species started going extinct.”

The research teased out these details by using 21,946 fossil specimens from areas of Nevada in the U.S. and the Yukon in Canada that were once ancient sea beds to paint a picture of graptolite evolution.

The analysis found that as ocean circulation patterns began to shift hundreds of thousands of years before the Ordovician extinction, graptolite communities that previously included a rich array of both shallow- and deep-sea species began to lose their diversity and complexity.

Deep-water graptolites became progressively rarer in comparison to their shallow-water counterparts, which came to dominate the ocean.

“There was less variety of organisms, and the rare organisms got rarer,” Sheets says. “In the aftermath of a forest fire in the modern world, you might find that there are fewer organisms left — that the ecosystem just doesn’t have the same structure and richness as before. That’s the same pattern we see here.”

The dwindling deep-sea graptolites were species that specialized in obtaining nutrients from low-oxygen zones of the ocean. A decrease in the availability of such habitats may have sparked the creatures’ decline, Sheets and Mitchell say.

“Temperature changes drive deep ocean circulations, and we think the deep-water graptolites lost their habitats as the climate changed,” Sheets says. “As the nature of the oceans shifted, their way of life went away.”

The research was supported by the U.S. National Science Foundation, Natural Sciences and Engineering Research Council of Canada, and Czech Academy of Sciences, and is a contribution to The International Geosciences Programme project 591 — The Early to Middle Paleozoic Revolution.

Insect camouflage 100 million years ago

2016-06-29T07:34:00.001-07:00

Those who go to a masked ball consciously slip into a different role, in order to avoid being recognized so quickly. Insects were already doing something very similar in the Cretaceous: They cloaked themselves in pieces of plants, grains of sand, or the remains of their prey, in order, for example, to be invisible to predators. An international research team, with participation from the University of Bonn, has now investigated such "invisibility cloaks" encased in amber. The custom-tailored "costumes" also permit conclusions about the habitat at the time. The results have now been published in the journal "Science Advances".

The larva of the lacewing attacks a pseudoscorpion and uses its powerful mouthparts to suck it dry. The larva then puts the remains of the dead prey on its back. The outlines of the lacewing are now unrecognizable. It looks more like a dead pseudoscorpion. This camouflage protects the lacewing against being recognized by predators and at the same makes it easier to hunt its own prey. "With this 'disguise', the lacewing larva pretends to be someone completely different", says Prof. Dr. Jes Rust of the Steinmann-Institute of the University of Bonn. "Using the pieces of its prey, it even takes on the smell of the pseudoscorpion".

The scene plays out in the Cretaceous and is recorded as a "snapshot" in amber. A research team under Dr. Bo Wang of the State Key Laboratory of Paleobiology and Stratigraphy in Nanjing (China) worked together with paleontologists from the University of Bonn and other scientists from China, USA, France, and England to examine a total of 35 insects preserved in amber. With the aid of grains of sand, plant residue, wood fibers, dust, or even the lifeless shells of their victims, the larvae achieved camouflage to perfection. The amber samples come from Myanmar, France, and Lebanon.

Evidence of early camouflage by insects is very rare

"These are very rare fossils, which give us unique insights into life more than 100 million years ago", says Dr. Torsten Wappler of the Steinmann-Institute of the University of Bonn, who joined Dr. Wang and Professor Rust to classify these oldest examples of camouflage. The research team was astonished to see the broad range of camouflage already used by insects in the Cretaceous.

Some larvae fashioned a kind of "knight's armor" from grains of sand, perhaps to protect against spider bites. In order to custom-tailor their "camo", they have even adapted their limbs for the purpose. The larvae were able to turn their legs about 180 degrees, in order to transport the grains of sand onto their back. Others cloaked themselves in plant residue, in order to become one with their surroundings, making them almost undetectable to predators. "It is very surprising how early in evolution such complex insect behavior developed: The larvae had to search actively for suitable 'camouflage material', pick it up, and cloak themselves with it", says Dr. Wang, who, with a stipend from the Humboldt-Stiftung foundation, has been a guest at the University of Bonn several times doing research.

Different paths to optimal camouflage

The scientists have analysed the pedigree of these "camouflage insects". Therefore, they know that the animals must have developed such strategies quite independently of one another, because they are not closely related. Professor Rust sums it up: "Apparently, camouflage offers many advantages for the user, for which reason it was 'invented' multiple times during evolution". Today there are still numerous types of insects that make themselves invisible, for instance using grains of sand, such as caddis-fly larvae in rivers and streams.

Based on the camouflage of the various amber insects, the research team reached conclusions about their habitat at the time. Examination of an ancestor of the ant lion under the microscope showed that the camouflage consisted of tiny pieces of fern. "These are fern species, which, for example, were the first types of plants to recolonize after fires", explains Dr. Wappler. Presumably, in the Cretaceous, a bush fire raged, which damaged the trees and stimulated unusually strong resin production. In this way, the "costumed" larvae were trapped in the tree resin and the scene preserved to this today.

Start Date for Plate Tectonics

2016-01-22T13:35:00.000-08:00

Earth has some special features that set it apart from its close cousins in the solar system, including large oceans of liquid water and a rich atmosphere with just the right ingredients to support life as we know it. Earth is also the only planet that has an active outer layer made of large tectonic plates that grind together and dip beneath each other, giving rise to mountains, volcanoes, earthquakes and large continents of land.

Geologists have long debated when these processes, collectively known as plate tectonics, first got underway. Some scientists propose that the process began as early as 4.5 billion years ago, shortly after Earth’s formation. Others suggest a much more recent start within the last 800 million years. A study from the University of Maryland provides new geochemical evidence for a middle ground between these two extremes: An analysis of trace element ratios that correlate to magnesium content suggests that plate tectonics began about 3 billion years ago. The results appear in the January 22, 2016 issue of the journal Science.

The image at left depicts what Earth might have looked like more than 3 billion years ago in the early Archean. The orange shapes represent the magnesium-rich proto-continents before plate tectonics started—although it is impossible to determine their precise shapes and locations. The ocean appears green due to a high amount of iron (Fe[II]) ions in the water at that time. The timeline traces the transition from a magnesium-rich (mafic) upper continental crust (UCC) to a magnesium-poor (felsic) UCC. Image credit: Ming Tang/UMD (click image to download hi-res version.)
The image at left depicts what Earth might have looked like more than 3 billion years ago in the early Archean. The orange shapes represent the magnesium-rich proto-continents before plate tectonics started—although it is impossible to determine their precise shapes and locations. The ocean appears green due to a high amount of iron (Fe[II]) ions in the water at that time. The timeline traces the transition from a magnesium-rich (mafic) upper continental crust (UCC) to a magnesium-poor (felsic) UCC. Image credit: Ming Tang/UMD (click image to download hi-res version.)

“By linking crustal composition and plate tectonics, we have provided first-order geochemical evidence for the onset of plate tectonics, which is a fundamental Earth science question,” said Ming Tang, a graduate student in geology at UMD and lead author of the study. “Because plate tectonics is necessary for the building of continents, this work also represents a further step in understanding when and how Earth’s continents formed.”

The study zeros in on one key characteristic of Earth’s crust that sets it apart geochemically from other terrestrial planets in the solar system. Compared with Mars, Mercury, Venus and even our own moon, Earth’s continental crust contains less magnesium. Early in its history, however, Earth’s crust more closely resembled its cousins, with a higher proportion of magnesium.

At some point, Earth’s crust evolved to contain more granite, a magnesium-poor rock that forms the basis of Earth’s continents. Many geoscientists agree that the start of plate tectonics drove this transition by dragging water underneath the crust, which is a necessary step to make granite.

“You can’t have continents without granite, and you can’t have granite without taking water deep into the Earth,” said Roberta Rudnick, former chair of the Department of Geology at UMD and senior author on the study. Rudnick, who is now a professor of earth sciences at the University of California, Santa Barbara, conducted this research while at UMD. “So at some point plate tectonics began and started bringing lots of water down into the mantle. The big question is when did that happen?”

A logical approach would be to look at the magnesium content in ancient rocks formed across a wide span of time, to determine when this transition toward low-magnesium crustal rocks began. However, this has proven difficult because the direct evidence—magnesium—has a pesky habit of washing away into the ocean once rocks are exposed to the surface.

Tang, Rudnick and Kang Chen, a graduate student at China University of Geosciences on a one and a half-year research visit to UMD, sidestepped this problem by looking at trace elements that are not soluble in water. These elements—nickel, cobalt, chromium and zinc—stay behind long after most of the magnesium has washed away. The researchers found that the ratios of these elements hold the key: higher ratios of nickel to cobalt and chromium to zinc both correlate to higher magnesium content in the original rock.

“To our knowledge, we are the first to discover this correlation and use this approach,” Tang said. “Because the ratios of these trace elements correlate to magnesium, they serve as a very reliable ‘fingerprint’ of past magnesium content.”

Tang and his coauthors compiled trace element data taken from a variety of ancient rocks that formed in the Archean eon, a time period between 4 and 2.5 billion years ago, and used it to determine the magnesium content in the rocks when they were first formed. They used these data to construct a computer model of the early Earth’s geochemical composition. This model accounted for how magnesium (specifically, magnesium oxide) content in the crust changed over time.

The results suggest that 3 billion years ago, the Earth’s crust had roughly 11 percent magnesium oxide by weight. Within a half billion years, that number had dropped to about 4 percent, which is very close to the 2 or 3 percent magnesium oxide seen in today’s crust. This suggested that plate tectonics began about 3 billion years ago, giving rise to the continents we see today.

“It’s really kind of a radical idea, to suggest that continental crust in Archean had that much magnesium,” said Rudnick, pointing out that Tang was the first to work out the correlation between trace element ratios and magnesium. “Ming’s discovery is powerful because he found that trace insoluble elements correlate with a major element, allowing us to address a long-standing question in Earth history.”

“Because the evolution of continental crust is linked to many major geological processes on Earth, this work may provide a basis for a variety of future studies of Earth history,” Tang said. “For example, weathering of this magnesium-rich crust may have affected the chemistry of the ancient ocean, where life on Earth evolved. As for the onset of plate tectonics, I don’t think this study will close the argument, but it certainly adds a compelling new dimension to the discussion.”

Ocean toxicity hampered the rapid evolution of complex life

2015-12-06T07:49:00.001-08:00

By examining rocks at the bottom of ancient oceans, an international group of researchers have revealed that arsenic concentrations in the oceans have varied greatly over time. But also that in the very early oceans, arsenic co-varied with the rise of atmospheric oxygen and coincided with the coming and going of global glaciations. The study was recently published in the Nature Group Journal, Scientific Reports.

“In the article we argue that when we first see the appearance of complex life on Earth, is when life have developed mechanisms to resist catastrophic chemical changes forced by global glaciations. And that this enabled the expansion of complex life in oceans, and paved the way for our own evolution”, says Dr Ernest Chi Fru of Stockholm University, who has led the research group.

The first appearance of oxygen in the atmosphere occurred at a time when marine arsenic concentrations were dramatically low, at about after 2.45 billion years ago (Siderian Period). This is also a period when Earth experienced its first known global glaciation. At the end of these glaciations, considerable rise in marine arsenic concentrations concurred with rapid demise of atmospheric oxygen.

The authors infer – from the way modern photosynthetic organisms react to changing marine arsenic concentrations – that this event was due to widespread ocean toxicity resulting from the release of toxic elements into the oceans when the ice melted.

A similar low and high arsenic content accompanied the coming and going of global glaciations at around 0.7 billion years ago (Cryogenian Period), which is when Earth first saw the appearance of complex life. While the low marine arsenic concentrations again coincide with a rapid rise in atmospheric oxygen content to near modern day levels at this time, the subsequent increase when the ice melted is not accompanied by atmospheric oxygen decline.

The study was performed by an international team of researchers from Sweden, Greece and France, led by Dr Ernest Chi Fru of Stockholm University. It was funded by the European Research Council.

The article Arsenic Stress after the Proterozoic Glaciations was recently published in Nature Group Journal, Scientific Reports.

New Evidence Adds Middle Permian to List of Major Extinctions

2015-04-19T13:43:00.000-07:00

Since the Cambrian Explosion, ecosystems have suffered repeated mass extinctions, with the "Big 5" crises being the most prominent. Twenty years ago, a sixth major extinction was recognized in the Middle Permian (262 million years ago) of China, when paleontologists teased apart losses from the "Great Dying" at the end of the period.

Until now, this Capitanian extinction was known only from equatorial settings, and its status as a global crisis was controversial. David P.G. Bond and colleagues provide the first evidence for severe Middle Permian losses amongst brachiopods in northern paleolatitudes (Spitsbergen). Their study shows that the Boreal crisis coincided with an intensification of marine oxygen depletion, implicating this killer in the extinction scenario.

The widespread loss of carbonates across the Boreal Realm also suggests a role for acidification. The new data cements the Middle Permian crisis's status as a true "mass extinction." Thus the "Big 5" extinctions should now be considered the "Big 6."

An abrupt extinction in the Middle Permian (Capitanian) of the Boreal Realm (Spitsbergen) and its link to anoxia and acidification
David P.G. Bond et al., University of Hull, Hull, UK. Published online ahead of print on 14 Apr. 2015; http://dx.doi.org/10.1130/B31216.1. This article is OPEN ACCESS (available for free online).

Earliest Evidence of Insect Caring for Its Young

2015-04-01T07:29:00.003-07:00

Scientists have uncovered the earliest fossilized evidence of an insect caring for its young.

The findings, published in the journal eLife, push back the earliest direct evidence of insect brood care by more than 50 million years, to the Cenomanian of the Cretaceous Period (~100 million years ago).

The new fossil is the only record of an adult female insect from the Mesozoic, an era that spanned roughly 180 million years. The Mesozoic era was the age of the reptiles and saw both the rise and fall of the dinosaurs, as well as the breakup of the supercontinent Pangaea.

The female ensign scale insect is preserved in a piece of amber retrieved from a mine in northern Myanmar (Burma). The specimen was trapped while carrying around 60 eggs and her first freshly hatched nymphs. The eggs and nymphs are encased in a wax-coated egg sac on the abdomen. This primitive form of brood care protects young nymphs from wet and dry conditions and from natural enemies until they have acquired their own thin covering of wax.

The behaviour has been so successful for promoting the survival of offspring that it is still common in insects today. Young nymphs hatch inside the egg sac and remain there for a few days before emerging into the outside world.

The findings may even offer an explanation for the early diversification of scale insects. The emergence of flowering plants and ants are thought to have been crucial for the rapid evolution of many new insect species, but they were not yet present during the evolutionary history of the ensign scale insects.

"Brood care could have been an important driver for the early radiation of scale insects, which occurred during the end of the Jurassic or earliest Cretaceous period during the Mesozoic era," says lead author Bo Wang, an associate professor at the Chinese Academy of Sciences.

Fossilised evidence of animals caring for their young is extremely rare, especially in insects. Wingless females were largely immobile, so were less likely to be accidentally buried. A cockroach from a similar period was reported carrying a mass of eggs, but cockroaches often deposit their eggs rather than brooding them. The only other direct evidence of brood care is from Cenozoic ambers, the era that extends to the present and began about 65 million years ago with the extinction of the dinosaurs.

"Although analysis seemed to suggest that ancient insects evolved brood care, this is the first direct, unequivocal evidence for the fossil record," says Wang.

The team have named this new species Wathondara kotejai after the goddess of earth in Buddhist mythology and the late Polish entomologist Jan Koteja.

Wang, B.,F. Xia,T.Wappler,E. Simon,H. Zhang, E. Jarzembowski, and J. Szwedo. 2015. Brood care in a 100-million-year-old scale insect. DOI:http://dx.doi.org/10.7554/eLife.05447

Early Cambrian Freshwater Radiation

2015-02-12T15:08:00.001-08:00

Fossils left by creatures burrowing in the sediments of an ancient riverbed push back the beginning of freshwater ecosystems by at least 85 million years. The find hints that there was little if any delay between the development of freshwater and marine ecosystems, contrary to what many biologists and paleontologists have proposed.

For a variety of reasons, paleontologists have suggested that life arose in marine environments and only later moved into freshwater. The lack of complex communities of organisms on land meant that freshwater ecosystems didn’t have a large source of nutrients, including organic substances, needed to nourish life. Also, organisms typically expend more energy in a freshwater environment to maintain their inner chemical balance, particularly their salty body fluids, than they do in a marine setting. And, says Mary Droser, a paleontologist at the University of California, Riverside, researchers hadn’t previously found much evidence for freshwater creatures in the fossil record until much after their marine counterparts appeared.

But now, Droser and colleague Martin Kennedy report in the June issue of Geology that they have found fossil burrows in ancient sandstones that they propose were deposited as sediments in a river. The pattern of individual grains in the rocks suggest that the material was deposited by a flow that ran only in one direction—a sign, the researchers say, that the ancient sand wasn’t exposed to the back-and-forth sloshing of waves and tides. The fossil burrows exist in seven different layers within eastern California’s Wood Creek formation, which was deposited sometime during the Early Cambrian (between 520 million to 542 million years ago), around the same time, or maybe even slightly before, a successful group of marine arthropods known as trilobites were scurrying across ocean floors worldwide.

Most of the fossil burrows are U-shaped, with a depth of less than 5 centimeters, and the exits are spaced between 1 to 1.5 centimeters apart. Diameters of the burrows are typically about 1 millimeter, Droser says. “These were tiny little animals.” The same sorts of burrows are found elsewhere in marine sediments of that era, but there they are typically about 10 times larger—a size disparity similar to that seen between modern-day creatures that burrow in freshwater sediments and their sea-floor-dwelling kin, she adds.

Because the sediments are coarse-grained and the burrows are relatively small, no scratch marks are preserved in the walls, Droser says. Therefore, it’s difficult to say what type of creature made the burrows. But some sort of invertebrate—possibly an arthropod, maybe even a worm—is the likeliest candidate. The large concentration of burrows in some layers suggests that the creatures lived in that ecosystem and weren’t merely migrating through the area.

Previously, the oldest evidence for freshwater ecosystems, including burrows and trackways in ancient pond deposits, comes from rocks about 435 million years old. So the newly described burrows push the origin of these ecosystems back 85 million to 107 million years, the researchers say.

“This is an exciting find,” says Anthony Martin, a paleontologist at Emory University in Atlanta. “There’s no doubt that there are trace fossils in these deposits.” Furthermore, he adds, there’s no doubt that the material in these sandstones were deposited by rivers. Nevertheless, Martin suggests, the burrow-makers could have been marine creatures, especially juveniles, that simply moved upstream in a bottom-hugging mass of saltwater during an extended drought or other period of low flow in the ancient river.

The burrows add to the mounting evidence that land-based ecosystems were evolving at the same time marine life was proliferating, during an era known as the Cambrian Explosion, Droser says.

The new find may cause other paleontologists to look at ancient riverine deposits more closely, Martin says. “A lot of people may not have looked simply because they didn’t expect to find anything"

Kennedy, M.J. and M.L. Droser. 2011. Early Cambrian metazoans in fluvial environments, evidence of the non-marine Cambrian radiation. Geology 39: 583-586.

How some of the first animals lived - and died

2014-08-12T08:12:00.000-07:00

New three-dimensional reconstructions show how some of the earliest animals on Earth developed, and provide some answers as to why they went extinct.

A bizarre group of uniquely-shaped organisms known as rangeomorphs may have been some of the earliest animals to appear on Earth, uniquely suited to ocean conditions 575 million years ago.

A new model devised by researchers at the University of Cambridge has resolved many of the mysteries around the structure, evolution and extinction of these ‘proto-animals’. The findings are reported today (11 August) in the journal Proceedings of the National Academy of Sciences of the United States of America.

Rangeomorphs were some of the earliest large organisms on Earth, existing during a time when most other forms of life were microscopic in size. Most rangeomorphs were about 10 centimetres high, although some were up to two metres in height.

These creatures were ocean dwellers which lived during the Ediacaran period, between 635 and 541 million years ago. Their bodies were made up of soft branches, each with many smaller side branches, forming a geometric shape known as a fractal, which can be seen in many familiar branching shapes such as fern leaves and even river networks.

Rangeomorphs were unlike any modern organism, which has made it difficult to determine how they fed, grew or reproduced, and therefore difficult to link them to any particular modern group. However, despite the fact that they looked like plants, evidence points to the fact that rangeomorphs were actually some of the earliest animals.

“We know that rangeomorphs lived too deep in the ocean for them to get their energy through photosynthesis as plants do,” said Dr Jennifer Hoyal Cuthill of Cambridge’s Department of Earth Sciences, who led the research. “It’s more likely that they absorbed nutrients directly from the sea water through the surface of their body. It would be difficult in the modern world for such large animals to survive only on dissolved nutrients.”

“The oceans during the Ediacaran period were more like a weak soup – full of nutrients such as organic carbon, whereas today suspended food particles are swiftly harvested by a myriad of animals,” said co-author Professor Simon Conway Morris.

Starting 541 million years ago, the conditions in the oceans changed quickly with the start of the Cambrian Explosion – a period of rapid evolution when most major animal groups first emerge in the fossil record and competition for nutrients increased dramatically.

Rangeomorphs have often been considered a ‘failed experiment’ of evolution as they died out so quickly once the Cambrian Explosion began in earnest, but this new analysis shows just how successful they once were.

Rangeomorphs almost completely filled the space surrounding them, with a massive total surface area. This made them very efficient feeders that were able to extract the maximum amount of nutrients from the ocean water.

“These creatures were remarkably well-adapted to their environment, as the oceans at the time were high in nutrients and low in competition,” said Dr Hoyal Cuthill. “Mathematically speaking, they filled their space in a nearly perfect way.”

Dr Hoyal Cuthill examined rangeomorph fossils from a number of locations worldwide, and used them to make the first computer reconstructions of the development and three-dimensional structure of these organisms, showing just how well-suited they were to their Ediacaran environment.

As the Cambrian Explosion began however, the rangeomorphs became ‘sitting ducks’, as they had no known means of defence from predators which were starting to evolve, and the changing chemical composition of the ocean meant that they could no longer get the nutrients they required to feed.

“As the Cambrian began, these Ediacaran specialists could no longer survive, and nothing quite like them has been seen again,” said Dr Hoyal Cuthill.

- See more at: http://www.cam.ac.uk/research/news/how-some-of-the-first-animals-lived-and-died#sthash.IrtqB1Df.dpuf

Rethinking Earth's Early Atmosphere

2013-12-05T10:44:00.000-08:00

A research team of biogeochemists at the University of California, Riverside has provided a new view on the relationship between the earliest accumulation of oxygen in the atmosphere, arguably the most important biological event in Earth history, and its relationship to the sulfur cycle.

A general consensus exists that appreciable oxygen first accumulated in Earth’s atmosphere around 2.4 to 2.3 billion years ago. Though this paradigm is built upon a wide range of geological and geochemical observations, the famous “smoking gun” for what has come to be known as the “Great Oxidation Event” (GOE) comes from the disappearance of anomalous fractionations in rare sulfur isotopes.

“These isotope fractionations, often referred to as ‘mass-independent fractionations,’ or ‘MIF’ signals, require both the destruction of sulfur dioxide by ultraviolet energy from the sun in an atmosphere without ozone and very low atmospheric oxygen levels in order to be transported and deposited in marine sediments,” said Christopher T. Reinhard, the lead author of the research paper and a former UC Riverside graduate student. “As a result, their presence in ancient rocks is interpreted to reflect vanishingly low atmospheric oxygen levels continuously for the first ~2 billion years of Earth’s history.”

However, diverse types of data are emerging that point to the presence of atmospheric oxygen, and, by inference, the early emergence of oxygenic photosynthesis hundreds of millions of years before these MIF signals disappear from the rock record. These observations motivated Reinhard and colleagues to explore the possible conditions under which inherited MIF signatures may have persisted in the rock record long after oxygen accumulated in the atmosphere.

Using a simple quantitative model describing how sulfur and its isotopes cycle through the Earth’s crust, the researchers discovered that under certain conditions these MIF signatures can persist within the ocean and marine sediments long after O2 increases in the atmosphere. Simply put, the weathering of rocks on the continents can transfer the MIF signal to the oceans and their sediments long after production of this fingerprint has ceased in an oxygenated atmosphere.

“This lag would blur our ability to date the timing of the GOE and would allow for dynamic rising and falling oxygen levels during a protracted transition from an atmosphere without oxygen to one rich in this life-giving gas,” Reinhard said.

Study results appear in Nature’s advanced online publication on April 24.

Reinhard explained that once MIF signals formed in an oxygen-poor atmosphere are captured in pyrite and other minerals in sedimentary rocks, they are recycled when those rocks are later uplifted as mountain ranges and the pyrite is oxidized.

“Under certain conditions, this will create a sort of ‘memory effect’ of these MIF signatures, providing a decoupling in time between the burial of MIF in sediments and oxygen accumulation at Earth’s surface,” he said.

According to the researchers, the key here is burying a distinct MIF signal in deep sea sediments, which are then subducted and removed from Earth’s surface.

“This would create a complementary signal in minerals that are weathered and delivered to the oceans, something that we actually see evidence of in the rock record,” said Noah Planavsky, the second author of the research paper and a former UC Riverside graduate student now at Caltech. “This signal can then be perpetuated through time without the need to generate it within the atmosphere contemporaneously.”

Reinhard, now a postdoctoral fellow at Caltech and soon to be an assistant professor at Georgia Institute of Technology, explained that although the researchers’ new model provides a plausible mechanism for reconciling recent conflicting data, this can only occur when certain key conditions are met — and these conditions are likely to have changed through time during Earth’s long early history.

“There is obviously much further work to do, but we hope that our model is one step toward a more integrated view of how Earth’s crust, mantle and atmosphere interact in the global sulfur cycle,” he said.

Timothy W. Lyons, a professor of biogeochemistry at UCR and the principal investigator of the research project noted that this is a fundamentally new and potentially very important way of looking at the sulfur isotope record and its relationship to biospheric oxygenation.

“The message is that sulfur isotope records, when viewed through the filter of sedimentary recycling, may challenge efforts to precisely date the GOE and its relationship to early life, while opening the door to the wonderful unknowns we should expect and embrace,” he said.

The research was supported by an O.K. Earl Postdoctoral Fellowship in the Division of Geological and Planetary Sciences at Caltech to Reinhard, a National Science Foundation postdoctoral fellowship to Planavsky, and a NASA Exobiology grant to Lyons.

Lichen-like Symbiosis from 600 Ma

2013-12-01T17:49:00.000-08:00

The fossil record of fungi and lichens is scarce. A team of researchers including Xunlai Yuan, Shuhai Xiao, and Tom Taylor report the discovery of lichen-like fossils, involving filamentous hyphae closely associated with round cyanobacteria or possibly algae. Lichens symbiotize with both bacteria and algae, and the fossils make it difficult to discern the exact affciities of the photobiont.

These cells were preserved in marine phosphorite of the Doushantuo Formation, in at Weng'an, South China. This formation preserves sediments from the Ediacaran Period, between 551 and 635 million years ago.

These fossils indicate that fungi developed symbiotic partnerships with photoautotrophs before the evolution of land plants.

Not All Minerals Were Present During Early Earth

2013-12-01T09:03:00.002-08:00

Life originated as a result of natural processes that exploited early Earth’s raw materials. Scientific models of life’s origins almost always look to minerals for such essential tasks as the synthesis of life’s molecular building blocks or the supply of metabolic energy. But this assumes that the mineral species found on Earth today are much the same as they were during Earth’s first 550 million years—the Hadean Eon—when life emerged. A new analysis of Hadean mineralogy challenges that assumption. It is published in American Journal of Science.

Carnegie’s Robert Hazen compiled a list of every plausible mineral species on the Hadean Earth and concludes that no more than 420 different minerals—about 8 percent of the nearly 5,000 species found on Earth today—would have been present at or near Earth’s surface.

“This is a consequence of the limited ways that minerals might have formed prior to 4 billion years ago,” Hazen explained. “Most of the 420 minerals of the Hadean Eon formed from magma—molten rock that slowly crystallized at or near Earth’s surface—as well as the alteration of those minerals when exposed to hot water.”

By contrast, thousands of mineral species known today are the direct result of growth by living organisms, such as shells and bones, as well as life’s chemical byproducts, such as oxygen from photosynthesis. In addition, hundreds of other minerals that incorporate relatively rare elements such as lithium, beryllium, and molybdenum appear to have taken a billion years or more to first appear because it is difficult to concentrate these elements sufficiently to form new minerals. So those slow-forming minerals are also excluded from the time of life’s origins.

“Fortunately for most origin-of-life models, the most commonly invoked minerals were present on early Earth,” Hazen said.

For example, clay minerals—sometimes theorized by chemists to trigger interesting reactions—were certainly available. Sulfide minerals, including reactive iron and nickel varieties, were also widely available to catalyze organic reactions. However, borate and molybdate minerals, which are relatively rare even today, are unlikely to have occurred on the Hadean Earth and call into question origin models that rely on those mineral groups.

Several questions remain unanswered and offer opportunities for further study of the paleomineralogy of the Hadean Eon. For example, the Hadean Eon differs from today in the frequent large impacts of asteroids and comets—thousands of collisions by objects with diameters from a mile up to 100 miles. Such impacts would have caused massive disruption of Earth’s crust, with extensive fracture zones that were filled with hot circulating water. Such hydrothermal areas could have created complex zones with many exotic minerals.

This study also raises the question of how other planets and moons evolved mineralogically. Hazen suggests that Mars today may have progressed only as far as Earth’s Hadean Eon. As such, Mars may be limited to a similar suite of no more than about 400 different mineral species. Thanks to the Curiosity rover, we may soon know if that’s the case.

Clay May Have Been Birthplace of Life

2013-11-17T18:35:00.001-08:00

Clay, a seemingly infertile blend of minerals, might have been the birthplace of life on Earth. Or at least of the complex biochemicals that make life possible, Cornell University biological engineers report in the Nov. 7 online issue of the journal Scientific Reports, published by Nature Publishing.

“We propose that in early geological history clay hydrogel provided a confinement function for biomolecules and biochemical reactions,” said Dan Luo, professor of biological and environmental engineering and a member of the Kavli Institute at Cornell for Nanoscale Science.

In simulated ancient seawater, clay forms a hydrogel – a mass of microscopic spaces capable of soaking up liquids like a sponge. Over billions of years, chemicals confined in those spaces could have carried out the complex reactions that formed proteins, DNA and eventually all the machinery that makes a living cell work. Clay hydrogels could have confined and protected those chemical processes until the membrane that surrounds living cells developed.

To further test the idea, the Luo group has demonstrated protein synthesis in a clay hydrogel. The researchers previously used synthetic hydrogels as a “cell-free” medium for protein production. Fill the spongy material with DNA, amino acids, the right enzymes and a few bits of cellular machinery and you can make the proteins for which the DNA encodes, just as you might in a vat of cells.

To make the process useful for producing large quantities of proteins, as in drug manufacturing, you need a lot of hydrogel, so the researchers set out to find a cheaper way to make it. Postdoctoral researcher Dayong Yang noticed that clay formed a hydrogel. Why consider clay? “It’s dirt cheap,” said Luo. Better yet, it turned out unexpectedly that using clay enhanced protein production.

But then it occurred to the researchers that what they had discovered might answer a long-standing question about how biomolecules evolved. Experiments by the late Carl Sagan of Cornell and others have shown that amino acids and other biomolecules could have been formed in primordial oceans, drawing energy from lightning or volcanic vents. But in the vast ocean, how could these molecules come together often enough to assemble into more complex structures, and what protected them from the harsh environment?

Scientists previously suggested that tiny balloons of fat or polymers might have served as precursors of cell membranes. Clay is a promising possibility because biomolecules tend to attach to its surface, and theorists have shown that cytoplasm – the interior environment of a cell – behaves much like a hydrogel. And, Luo said, a clay hydrogel better protects its contents from damaging enzymes (called “nucleases”) that might dismantle DNA and other biomolecules.

As further evidence, geological history shows that clay first appeared – as silicates leached from rocks – just at the time biomolecules began to form into protocells – cell-like structures, but incomplete – and eventually membrane-enclosed cells. The geological events matched nicely with biological events.

How these biological machines evolved remains to be explained, Luo said. For now his research group is working to understand why a clay hydrogel works so well, with an eye to practical applications in cell-free protein production.

Luo collaborated with professor Max Lu of the Australian Institute for Bioengineering and Nanotechnology at the University of Queensland in Australia. The work was performed at the Cornell Center for Materials Research Shared Facilities, supported by the National Science Foundation.

Climate puzzle over origins of life on Earth

2013-10-13T10:31:00.001-07:00

The mystery of why life on Earth evolved when it did has deepened with the publication of a new study in the journal Science.

Scientists at the CRPG-CNRS University of Lorraine, The University of Manchester and the Institut de Physique du Globe de Paris have ruled out a theory as to why the planet was warm enough to sustain the planet’s earliest life forms when the Sun’s energy was roughly three-quarters the strength it is today.

Life evolved on Earth during the Archean, between 3.8 and 2.4 billion years ago, but the weak Sun should have meant the planet was too cold for life to take hold at this time; scientists have therefore been trying to find an explanation for this conundrum, what is dubbed the ‘faint, young Sun paradox’.

“During the Archean the solar energy received at the surface of the Earth was about 20 to 25% lower than present,” said study author, Dr Ray Burgess, from Manchester’s School of Earth, Atmospheric and Environmental Sciences. “If the greenhouse gas composition of the atmosphere was comparable to current levels then the Earth should have been permanently glaciated but geological evidence suggests there were no global glaciations before the end of the Archean and that liquid water was widespread.”

One explanation for the puzzle was that greenhouse gas levels – one of the regulators of the Earth’s climate – were significantly higher during the Archean than they are today.

“To counter the effect of the weaker Sun, carbon dioxide concentrations in the Earth’s atmosphere would need to have been 1,000 times higher than present,” said lead author Professor Bernard Marty, from the CRPG-CNRS University of Lorraine. “However, ancient fossil soils – the best indicators of ancient carbon dioxide levels in the atmosphere – suggest only modest levels during the Archean. Other atmospheric greenhouse gases were also present, in particular ammonia and methane, but these gases are fragile and easily destroyed by ultraviolet solar radiation, so are unlikely to have had any effect.”

But another climate-warming theory – one the team wanted to test – is that the amount of nitrogen could have been higher in the ancient atmosphere, which would amplify the greenhouse effect of carbon dioxide and allow the Earth to remain ice-free.

The team analysed tiny samples of air trapped in water bubbles in quartz from a region of northern Australia that has extremely old and exceptionally well-preserved rocks.

“We measured the amount and isotopic abundances of nitrogen and argon in the ancient air,” said Professor Marty. “Argon is a noble gas which, being chemically inert, is an ideal element to monitor atmospheric change. Using the nitrogen and argon measurements we were able to reconstruct the amount and isotope composition of the nitrogen dissolved in the water and, from that, the atmosphere that was once in equilibrium with the water.”

The researchers found that the partial pressure of nitrogen in the Archean atmosphere was similar, possibly even slightly lower, than it is at present, ruling out nitrogen as one of the main contenders for solving the early climate puzzle.

Dr Burgess added: “The amount of nitrogen in the atmosphere was too low to enhance the greenhouse effect of carbon dioxide sufficiently to warm the planet. However, our results did give a higher than expected pressure reading for carbon dioxide – at odds with the estimates based on fossil soils – which could be high enough to counteract the effects of the faint young Sun and will require further investigation.”

One further important finding made by the team was that the nitrogen isotope ratio (14N and 15N) of the Archean atmosphere was very similar to that of modern-day nitrogen. The two isotopes are lost to space at different rates, so the ratio is a sensitive probe of atmospheric loss from the upper atmosphere, which can occur by interaction of the atmosphere with the solar wind. The Earth's magnetic field effectively shields the planet and prevent this happening; if the early Earth did not have a strong magnetic field then the interaction would have been much more intense and the loss of atmosphere to space greater, leading to a significant change in the isotopic composition of nitrogen. (This is exactly what is believed to have happened to the atmosphere of Mars, a planet with a weak magnetic field.) The constancy of the isotopic ratio of nitrogen from the Archean to the present day attests to the presence of a significant geomagnetic field since that time, requiring an intensity of at least 50% of the current magnetic field.

A copy of the paper, ‘Nitrogen Isotopic Composition and Density of the Archean Atmosphere,’ published in Science on Friday, 4 October, is available on request.

For further information contact:

Aeron Haworth
Media Relations
Faculty of Engineering and Physical Sciences
The University of Manchester

Tel: 0161 275 8387
Mob: 07717 881563
Email: aeron.haworth@manchester.ac.uk

Foraminfera may have Caused Decline of Stromatolites

2013-07-14T08:30:00.001-07:00

The widespread disappearance of stromatolites, the earliest visible manifestation of life on Earth, may have been driven by single-celled organisms called foraminifera.

The findings, by scientists at Woods Hole Oceanographic Institution (WHOI); Massachusetts Institute of Technology; the University of Connecticut; Harvard Medical School; and Beth Israel Deaconess Medical Center, Boston, were published online the week of May 27 in the Proceedings of the National Academy of Sciences.

Stromatolites (“layered rocks”) are structures made of calcium carbonate and shaped by the actions of photosynthetic cyanobacteria and other microbes that trapped and bound grains of coastal sediment into fine layers. They showed up in great abundance along shorelines all over the world about 3.5 billion years ago.

“Stromatolites were one of the earliest examples of the intimate connection between biology—living things—and geology—the structure of the Earth itself,” said WHOI geobiologist Joan Bernhard, lead author of the study.

The growing bacterial community secreted sticky compounds that bound the sediment grains around themselves, creating a mineral “microfabric” that accumulated to become massive formations. Stromatolites dominated the scene for more than two billion years, until late in the Proterozoic Eon.

“Then, around 1 billion years ago, their diversity and their fossil abundance begin to take a nosedive,” said Bernhard. All over the globe, over a period of millions of years, the layered formations that had been so abundant and diverse began to disappear. To paleontologists, their loss was almost as dramatic as the extinction of the dinosaurs millions of years later, although not as complete: Living stromatolites can still be found today, in limited and widely scattered locales, as if a few velociraptors still roamed in remote valleys.

While the extinction of the dinosaurs has largely been explained by the impact of a large meteorite, the crash of the stromatolites remains unsolved. “It’s one of the major questions in Earth history,” said WHOI microbial ecologist Virginia Edgcomb, a co-author on the paper.

Just as puzzling is the sudden appearance in the fossil record of different formations called thrombolites (“clotted stones”). Like stromatolites, thrombolites are produced through the action of microbes on sediment and minerals. Unlike stromatolites, they are clumpy, rather than finely layered.

It’s not known whether stromatolites became thrombolites, or whether thrombolites arose independently of the decline in strombolites. Hypotheses proposed to explain both include changes in ocean chemistry and the appearance of multicellular life forms that might have preyed on the microbes responsible for their structure.

Bernhard and Edgcomb thought foraminifera might have played a role. Foraminifera (or “forams,” for short) are protists, the kingdom that includes amoeba, ciliates, and other groups formerly referred to as “protozoa.” They are abundant in modern-day oceanic sediments, where they use numerous slender projections called pseudopods to engulf prey, to move, and to continually explore their immediate environment. Despite their known ability to disturb modern sediments, their possible role in the loss of stromatolites and appearance of thrombolites had never been considered.

The researchers examined modern stromatolites and thrombolites from Highborne Cay in the Bahamas for the presence of foraminifera. Using microscopic and rRNA sequencing techniques, they found forams in both kinds of structures. Thrombolites were home to a greater diversity of foraminifera and were especially rich in forams that secrete an organic sheath around themselves. These “thecate” foraminifera were probably the first kinds of forams to evolve, not long (in geologic terms) before stromatolites began to decline.

“The timing of their appearance corresponds with the decline of layered stromatolites and the appearance of thrombolites in the fossil record,” said Edgcomb. “That lends support to the idea that it could have been forams that drove their evolution.”

Next, Bernhard, Edgcomb, and postdoctoral investigator Anna McIntyre-Wressnig created an experimental scenario that mimicked what might have happened a billion years ago.

“No one will ever be able to re-create the Proterozoic exactly, because life has evolved since then, but you do the best you can,” Edgcomb said.

They started with chunks of modern-day stromatolites collected at Highborne Cay, and seeded them with foraminifera found in modern-day thrombolites. Then they waited to see what effect, if any, the added forams had on the stromatolites.

After about six months, the finely layered arrangement characteristic of stromatolites had changed to a jumbled arrangement more like that of thrombolites. Even their fine structure, as revealed by CAT scans, resembled that of thrombolites collected from the wild. “The forams obliterated the microfabric,” said Bernhard.

That result was intriguing, but it did not prove that the changes in the structure were due to the activities of the foraminifera. Just being brought into the lab might have caused the changes. But the researchers included a control in their experiment: They seeded foraminifera onto freshly-collected stromatolites as before, but also treated them with colchicine, a drug that prevented them from sending out pseudopods. “They’re held hostage,” said Bernhard. “They’re in there, but they can’t eat, they can’t move.”

After about six months, the foraminifera were still present and alive—but the rock’s structure had not become more clotted like a thrombolite. It was still layered.

The researchers concluded that active foraminifera can reshape the fabric of stromatolites and could have instigated the loss of those formations and the appearance of thrombolites.

Finding the Path to Earth's Early Oxygen

2013-06-30T07:41:00.000-07:00

For most terrestrial life on Earth, oxygen is necessary for survival. But the planet's atmosphere did not always contain this life-sustaining substance, and one of science's greatest mysteries is how and when oxygenic photosynthesis -- the process responsible for producing oxygen on Earth through the splitting of water molecules -- first began. Now, a team led by geobiologists at the California Institute of Technology (Caltech) has found evidence of a precursor photosystem involving manganese that predates cyanobacteria, the first group of organisms to release oxygen into the environment via photosynthesis.

The findings, outlined in the June 24 early edition of the Proceedings of the National Academy of Sciences (PNAS), strongly support the idea that manganese oxidation -- which, despite the name, is a chemical reaction that does not have to involve oxygen -- provided an evolutionary stepping-stone for the development of water-oxidizing photosynthesis in cyanobacteria.

"Water-oxidizing or water-splitting photosynthesis was invented by cyanobacteria approximately 2.4 billion years ago and then borrowed by other groups of organisms thereafter," explains Woodward Fischer, assistant professor of geobiology at Caltech and a coauthor of the study. "Algae borrowed this photosynthetic system from cyanobacteria, and plants are just a group of algae that took photosynthesis on land, so we think with this finding we're looking at the inception of the molecular machinery that would give rise to oxygen."

Photosynthesis is the process by which energy from the sun is used by plants and other organisms to split water and carbon dioxide molecules to make carbohydrates and oxygen. Manganese is required for water splitting to work, so when scientists began to wonder what evolutionary steps may have led up to an oxygenated atmosphere on Earth, they started to look for evidence of manganese-oxidizing photosynthesis prior to cyanobacteria. Since oxidation simply involves the transfer of electrons to increase the charge on an atom -- and this can be accomplished using light or O2 -- it could have occurred before the rise of oxygen on this planet.

"Manganese plays an essential role in modern biological water splitting as a necessary catalyst in the process, so manganese-oxidizing photosynthesis makes sense as a potential transitional photosystem," says Jena Johnson, a graduate student in Fischer's laboratory at Caltech and lead author of the study.

To test the hypothesis that manganese-based photosynthesis occurred prior to the evolution of oxygenic cyanobacteria, the researchers examined drill cores (newly obtained by the Agouron Institute) from 2.415 billion-year-old South African marine sedimentary rocks with large deposits of manganese.

Manganese is soluble in seawater. Indeed, if there are no strong oxidants around to accept electrons from the manganese, it will remain aqueous, Fischer explains, but the second it is oxidized, or loses electrons, manganese precipitates, forming a solid that can become concentrated within seafloor sediments.

"Just the observation of these large enrichments -- 16 percent manganese in some samples -- provided a strong implication that the manganese had been oxidized, but this required confirmation," he says.

To prove that the manganese was originally part of the South African rock and not deposited there later by hydrothermal fluids or some other phenomena, Johnson and colleagues developed and employed techniques that allowed the team to assess the abundance and oxidation state of manganese-bearing minerals at a very tiny scale of 2 microns.

"And it's warranted -- these rocks are complicated at a micron scale!" Fischer says. "And yet, the rocks occupy hundreds of meters of stratigraphy across hundreds of square kilometers of ocean basin, so you need to be able to work between many scales -- very detailed ones, but also across the whole deposit to understand the ancient environmental processes at work."

Using these multiscale approaches, Johnson and colleagues demonstrated that the manganese was original to the rocks and first deposited in sediments as manganese oxides, and that manganese oxidation occurred over a broad swath of the ancient marine basin during the entire timescale captured by the drill cores.

"It's really amazing to be able to use X-ray techniques to look back into the rock record and use the chemical observations on the microscale to shed light on some of the fundamental processes and mechanisms that occurred billions of years ago," says Samuel Webb, coauthor on the paper and beam line scientist at the SLAC National Accelerator Laboratory at Stanford University, where many of the study's experiments took place. "Questions regarding the evolution of the photosynthetic pathway and the subsequent rise of oxygen in the atmosphere are critical for understanding not only the history of our own planet, but also the basics of how biology has perfected the process of photosynthesis."

Once the team confirmed that the manganese had been deposited as an oxide phase when the rock was first forming, they checked to see if these manganese oxides were actually formed before water-splitting photosynthesis or if they formed after as a result of reactions with oxygen. They used two different techniques to check whether oxygen was present. It was not -- proving that water-splitting photosynthesis had not yet evolved at that point in time. The manganese in the deposits had indeed been oxidized and deposited before the appearance of water-splitting cyanobacteria. This implies, the researchers say, that manganese-oxidizing photosynthesis was a stepping-stone for oxygen-producing, water-splitting photosynthesis.

"I think that there will be a number of additional experiments that people will now attempt to try and reverse engineer a manganese photosynthetic photosystem or cell," Fischer says. "Once you know that this happened, it all of a sudden gives you reason to take more seriously an experimental program aimed at asking, 'Can we make a photosystem that's able to oxidize manganese but doesn't then go on to split water? How does it behave, and what is its chemistry?' Even though we know what modern water splitting is and what it looks like, we still don't know exactly how it works. There is a still a major discovery to be made to find out exactly how the catalysis works, and now knowing where this machinery comes from may open new perspectives into its function -- an understanding that could help target technologies for energy production from artificial photosynthesis. "

Next up in Fischer's lab, Johnson plans to work with others to try and mutate a cyanobacteria to "go backwards" and perform manganese-oxidizing photosynthesis. The team also plans to investigate a set of rocks from western Australia that are similar in age to the samples used in the current study and may also contain beds of manganese. If their current study results are truly an indication of manganese-oxidizing photosynthesis, they say, there should be evidence of the same processes in other parts of the world.

"Oxygen is the backdrop on which this story is playing out on, but really, this is a tale of the evolution of this very intense metabolism that happened once -- an evolutionary singularity that transformed the planet," Fischer says. "We've provided insight into how the evolution of one of these remarkable molecular machines led up to the oxidation of our planet's atmosphere, and now we're going to follow up on all angles of our findings."

Funding for the research outlined in the PNAS paper, titled "Manganese-oxidizing photosynthesis before the rise of cyanobacteria," was provided by the Agouron Institute, NASA's Exobiology Branch, the David and Lucile Packard Foundation, and the National Science Foundation Graduate Research Fellowship program. Joseph Kirschvink, Nico and Marilyn Van Wingen Professor of Geobiology at Caltech, also contributed to the study along with Katherine Thomas and Shuhei Ono from the Massachusetts Institute of Technology.

J. E. Johnson, S. M. Webb, K. Thomas, S. Ono, J. L. Kirschvink, W. W. Fischer. Manganese-oxidizing photosynthesis before the rise of cyanobacteria.Proceedings of the National Academy of Sciences, 2013; DOI: 10.1073/pnas.1305530110

Jurassic Ecosystems Were Similar to Modern: Animals Flourish Among Lush Plants

2013-04-07T15:36:00.001-07:00

CO2 levels in fossil soils from the Late Jurassic confirm that climate, vegetation and animal richness varied across the planet 150 million years ago, suggesting future human changes to global climate will heavily impact plant and animal life.

In modern ecosystems, it's widely known that animals flourish in regions where the climate and landscape produce lush vegetation.

A new study set out to discover whether that same relationship held true 150 million years ago during the Late Jurassic when dinosaurs roamed Earth.

"The assumption has been that ancient ecosystems worked just like our modern ecosystems," said paleontologist and lead author Timothy S. Myers, Southern Methodist University, Dallas. "We wanted to see if this was, in fact, the case."

To test the theory, Myers analyzed fossil soils from the Late Jurassic by measuring the ratios of carbon isotopes. His analysis indicated that the Jurassic soils contained high levels of CO2 from vegetation.

From that, Myers was able to infer the presence of lush plant life in certain regions during the Jurassic. The soils came from locales where scientists previously have gathered animal fossils -- North America, Europe and Africa. Combining the data with the known fossil sampling allowed Myers to confirm that the modern relationship between animals and vegetation held true even millions of years ago.

"Our analysis represents the first time that anyone has tried to apply ecological modeling to this relationship in the fossil record," Myers said.

Relatively few places in the world are well-sampled for terrestrial fossils, so Myers' discovery of a new use for an already existing method represents a useful tool, he said. The new use allows scientists to tap the geochemical data of soils from anywhere in the world and from other geologic time periods to infer the relative abundance of plants and animals, particularly for areas where fossils are lacking.

"This not only provides a more complete picture of the ancient landscape and climate in which ancient animals lived," Myers said. "It also illustrates that climate and biota have been ecologically connected for many millions of years and that future human-caused changes to global climate will have profound impacts on plant and animal life around the world."

Myers and his co-researchers reported the findings inPaleobiology, "Estimating Soil pCO2 Using Paleosol Carbonates: Implications for the Relationship Between Primary Productivity and Faunal Richness in Ancient Terrestrial Ecosystems."

Co-authors were SMU sedimentary geochemist Neil J. Tabor and paleontologists Louis L. Jacobs, SMU, and Octávio Mateus, New University of Lisbon, Portugal.

"Devising new and creative methods to understand how Earth and life have functioned together in the past is the foundation for predicting the future of life on our planet," said Jacobs, a vertebrate paleontologist and professor in SMU's Roy M. Huffington Department of Earth Sciences. "It is the only approach that provides a long enough perspective of what is possible."

New method applied to old hypothesis confirms regional variability
Typically researchers count the number of animal species discovered in a region to determine how many different types of animals once lived there. Scientists call that a measure of faunal richness.

Myers took a different approach. Using a traditional method typically used to estimate carbon dioxide in the ancient atmosphere, Myers instead applied it to estimate the amount of CO2 in ancient soils.

Measurements were taken from nodules of calcite that form in soil as a result of wet and dry seasons. These nodules take on the isotopic signature of the CO2 gas around them, which is a mixture derived from two sources: the atmosphere, which leaves a more positive isotopic signature, and plants decaying in the soil, which leave a more negative isotopic signature.

A higher volume of CO2 from plants indicates a lusher, wetter environment.

"There's a lot more litter fall in an environment with a lot of plants, and that produces a lot of organic material in the soil, creating CO2. So we see more soil-produced CO2, displacing the atmospheric CO2. These are established relationships," Myers said.

"Our method can be used to infer relative levels of richness for areas where soils have been preserved, but where fossils are lacking because conditions were unsuitable for their preservation," he said.

The research demonstrates creative use of existing geological data, said co-author Tabor, an expert in ancient soil in SMU's Roy M. Huffington Department of Earth Sciences.

"Vertebrate paleontologists have been accumulating information about vertebrate fossils in the Jurassic for well over 100 years. In addition, geochemists have been systematically sampling the composition of ancient soils for several decades," Tabor said. "In these respects, the data that are the foundation of this study are not extraordinary. What is remarkable, though, is combining the paleontology and geochemistry data to answer large-scale questions that extend beyond the data points -- specifically, to answer questions about ancient ecosystems."

Data from Morrison Formation, Central Africa and PortugalMyers tested Upper Jurassic soil nodules collected from the Morrison Formation in the western United States. The formation extends from Montana to New Mexico and has been the source of many dinosaur fossil discoveries.

He also analyzed Upper Jurassic soil nodules from Portugal, another location well-sampled for dinosaur fossils. The region's paleoclimate was broadly similar to that of the Morrison Formation.

In addition, Myers tested a small Upper Jurassic core sample from Central Africa, where there's no evidence of any major terrestrial life. Unique minerals in the rocks indicate that the region had an arid environment during the Late Jurassic.

Based on their hypothesis, the researchers expected to see regional variations in plant productivity -- the amount of new growth produced in an area over time, which is an indirect measure of the amount of plant life in an environment. Forests, savannas and deserts all have different amounts of plant productivity, although those specific ecosystems can't be identified on the basis of plant productivity alone.

The researchers expected to see higher plant productivity for Portugal than for the Morrison Formation, with the lowest productivity in Central Africa.

"Essentially that's what we found," Myers said. "We understand it's tenuous and not a trend, but few places in the world are well-sampled. However, it's still a useful tool for places where all we have are the soil nodules, without well-preserved fauna."

Soil nodules are fairly common, Myers said. They form as a result of seasonally dry conditions and may be preserved in all but the wettest environments. Since they harden into mineralized clods, they are easy to spot and sample as they weather out of ancient soil profiles.

CO2 in ancient calcite nodules offers key to ancient climate

From the analysis scientists can draw a more complete picture of the ancient landscape and climate in which prehistoric animals lived.

"The Jurassic is thought of as very warm, very wet, with lots of dinosaurs," said Myers, research curator for SMU's Shuler Museum of Paleontology. "But we see from our analysis that there was regional variability during the Late Jurassic in the climate and in the abundance of animals across the planet."

The Late Jurassic extended from 160 million years ago to 145 million years ago.

Timothy S. Myers, Neil J. Tabor, Louis L. Jacobs, Octávio Mateus. Estimating soilpCO2using paleosol carbonates: implications for the relationship between primary productivity and faunal richness in ancient terrestrial ecosystems. Paleobiology, 2012; 38 (4): 585 DOI:10.1666/11005.1

New Data Challenge Old Views About Evolution of Early Life

2012-12-31T12:03:00.001-08:00

Diorama of Precamrian Sea

A research team led by biogeochemists at the University of California, Riverside has tested a popular hypothesis in paleo-ocean chemistry, and found little evidence for it.

The fossil record indicates that eukaryotes — single-celled and multicellular organisms with more complex cellular structures compared to prokaryotes, such as bacteria — show limited morphological and functional diversity before 800-600 million years ago. Many researchers attribute the delayed diversification and proliferation of eukaryotes, which culminated in the appearance of complex animals about 600 million years ago, to very low levels of the trace metal zinc in seawater.

As it is for humans, zinc is essential for a wide range of basic cellular processes. Zinc-binding proteins, primarily located in the cell nucleus, are involved in the regulation of gene transcription.

Eukaryotes have increasingly incorporated zinc-binding structures during the last third of their evolutionary history and still employ both early- and late-evolving zinc-binding protein structures. Zinc is, therefore, of particular importance to eukaryotic organisms. And so it is not a stretch to blame the 1-2-billion-year delay in the diversification of eukaryotes on low bioavailability of this trace metal.

But after analyzing marine black shale samples from North America, Africa, Australia, Asia and Europe, ranging in age from 2.7 billion years to 580 million years old, the researchers found that the shales reflect high seawater zinc availability and that zinc concentrations during the Proterozoic (2.5 billion to 542 million years ago) were similar to modern concentrations. Zinc, the researchers posit, was never biolimiting.

Study results appear online Dec. 23 in Nature Geoscience.

“We argue that the concentration of zinc in ancient marine black shales is directly related to the concentrations of zinc in seawater and show that zinc is abundant in these rocks throughout Earth’s history,” said Clint Scott, the first author of the research paper and a former UC Riverside graduate student. “We found no evidence for zinc biolimitation in seawater.”

Scott, now a research geologist with the U.S. Geological Survey, explained that the connection between zinc limitation and the evolution of eukaryotes was based largely on the hypothesis that Proterozoic oceans were broadly sulfidic. Under broadly sulfidic conditions, zinc should have been scarce because it would have rapidly precipitated in the oceans, he explained.

“However, a 2011 research paper in Nature also published by our group at UCR demonstrated that Proterozoic oceans were more likely broadly ferruginous — that is, low in oxygen and iron-rich — and that sulfidic conditions were more restricted than previously thought,” said Scott, who performed the research in the lab of Timothy Lyons, a professor of biogeochemistry and the principal investigator of the research project.

The research team argues that ferruginous deep oceans, combined with large hydrothermal fluxes of zinc via volcanic activity on the seafloor, maintained high levels of dissolved zinc throughout the oceans and provided a relatively stable marine reservoir of the trace metal over the past 2.7 billion years.

“The key challenge in understanding the early evolution of life is recognizing the environmental conditions under which that life first appeared and diversified,” Lyons said. “We have taken a very direct approach that specifically tracks the availability of essential micronutrients, and, to our surprise, zinc supplies in ancient seawater were much higher and less variable than previously imagined.

“We can imagine for the first time,” he quipped, “that zinc supplements were not on the shopping lists of our early eukaryotic ancestors, and so we better find another reason to explain the mysterious delay in their rise in the ocean.”

Scott, who graduated with a doctoral degree in geological sciences from UCR in 2009, and Lyons were joined in the study by Noah J. Planavsky, a former UCR graduate student in Lyons’ lab; Chris L. Dupont at the J. Craig Venter Institute, La Jolla, Calif.; Brian Kendall and Ariel D. Anbar at Arizona State University; Benjamin C. Gill at Virginia Polytechnic Institute and State University and also a former member of the Lyons lab; Leslie J. Robbins and Kurt O. Konhauser at the University of Alberta, Canada; Kathryn F. Husband and Simon W. Poulton at the University of Leeds, United Kingdom; Gail L. Arnold at the Max Planck Institute for Marine Microbiology, Germany; Boswell A. Wing at McGill University, Canada; and Andrey Bekker at the University of Manitoba, Canada.

The idea for the study was a direct consequence of the 2011 Nature paper by Planavsky, Scott, Lyons and others that challenged the hypothesis of broadly sulfidic oceans.

Mysterious Ordovician Fossil from Cincinnati

2012-10-21T11:08:00.001-07:00

Around 450 million years ago, shallow seas covered the Cincinnati region and harbored one very large and now very mysterious organism. Despite its size, no one has ever found a fossil of this “monster” until its discovery by an amateur paleontologist last year.

The fossilized specimen, a roughly elliptical shape with multiple lobes, totaling almost seven feet in length, will be unveiled at the North-Central Section 46th Annual Meeting of the Geological Society of America, April 24, in Dayton, Ohio. Participating in the presentation will be amateur paleontologist Ron Fine of Dayton, who originally found the specimen, Carlton E. Brett and David L. Meyer of the University of Cincinnati geology department, and Benjamin Dattilo of the Indiana University Purdue University Fort Wayne geosciences faculty.

UC Paleontologist David Meyer, left and Carlton Brett, right, flank Ron Fine, who discovered the large fossil spread out on the table.

Fine is a member of the Dry Dredgers, an association of amateur paleontologists based at the University of Cincinnati. The club, celebrating its 70th anniversary this month, has a long history of collaborating with academic paleontologists.

“I knew right away that I had found an unusual fossil,” Fine said. “Imagine a saguaro cactus with flattened branches and horizontal stripes in place of the usual vertical stripes. That’s the best description I can give.”

The layer of rock in which he found the specimen near Covington, Kentucky, is known to produce a lot of nodules or concretions in a soft, clay-rich rock known as shale.

“While those nodules can take on some fascinating, sculpted forms, I could tell instantly that this was not one of them,” Fine said. “There was an ‘organic’ form to these shapes. They were streamlined.”

Fine was reminded of streamlined shapes of coral, sponges and seaweed as a result of growing in the presence of water currents.

“And then there was that surface texture,” Fine said. “Nodules do not have surface texture. They're smooth. This fossil had an unusual texture on the entire surface.”

For more than 200 years, the rocks of the Cincinnati region have been among the most studied in all of paleontology, and the discovery of an unknown, and large, fossil has professional paleontologists scratching their heads.

“It’s definitely a new discovery,” Meyer said. “And we’re sure it’s biological. We just don’t know yet exactly what it is.”

To answer that key question, Meyer said that he, Brett, and Dattilo were working with Fine to reconstruct a timeline working backward from the fossil, through its preservation, burial, and death to its possible mode of life.

“What things had to happen in what order?” Meyer asked. “Something caused a directional pattern. How did that work? Was it there originally or is it post-mortem? What was the burial event? How did the sediment get inside? Those are the kinds of questions we have.”

It has helped, Meyer said, that Fine has painstakingly reassembled the entire fossil. This is a daunting task, since the large specimen is in hundreds of pieces.

“I’ve been fossil collecting for 39 years and never had a need to excavate. But this fossil just kept going, and going, and going,” Fine said. “I had to make 12 trips, over the course of the summer, to excavate more material before I finally found the end of it.”

Even then he still had to guess as to the full size, because it required countless hours of cleaning and reconstruction to put it all back together.

“When I finally finished it was three-and-a-half feet wide and six-and-a-half feet long,” Fine said. “In a world of thumb-sized fossils that’s gigantic!”

Meyer, co-author of A Sea without Fish: Life in the Ordovician Sea of the Cincinnati Region, agreed that it might be the largest fossil recovered from the Cincinnati area.

“My personal theory is that it stood upright, with branches reaching out in all directions similar to a shrub,” Fine said. “If I am right, then the upper-most branch would have towered nine feet high. “

As Meyer, Brett and Dattilo assist Fine in studying the specimen, they have found a clue to its life position in another fossil. The mystery fossil has several small, segmented animals known as primaspid trilobites attached to its lower surface. These small trilobites are sometimes found on the underside of other fossilized animals, where they were probably seeking shelter.

“A better understanding of that trilobite’s behavior will likely help us better understand this new fossil,” Fine said.

Although the team has reached out to other specialists, no one has been able to find any evidence of anything similar having been found. The mystery monster seems to defy all known groups of organisms, Fine said, and descriptions, even pictures, leave people with more questions than answers.

The presentation April 24 is a “trial balloon,” Meyer said, an opportunity for the team to show a wide array of paleontologists what the specimen looks like and to collect more hypotheses to explore.

“We hope to get a lot of people stopping by to offer suggestions,” he said.

In the meantime, the team is playing around with potential names. They are leaning toward “Godzillus.”

From University of Cincinnati news

Let There Be Life!

2011-10-23T10:52:00.000-07:00

New University of Alberta research shows the first evidence that the first oxygen-breathing bacteria occupied and thrived on land 100 million years earlier than previously thought. The researchers show that the most primitive form of aerobic-respiring life on land came into existence 2.48 billion years ago.

The research team, led by U of A geomicrobiologist Kurt Konhauser, made their find by investigating a link between atmospheric oxygen levels and rising concentrations of chromium in the rock of ancient seabeds.
“We suggest that the jump in chromium levels was triggered by the oxidation of the mineral pyrite (fool’s gold) on land,” said Konhauser.

Pyrite oxidation is a simple chemical process driven by two things: bacteria and oxygen. The researchers say this proves that oxygen levels in Earth’s atmosphere increased dramatically during that time.

“Aerobic bacteria broke down the pyrite, which released acid that dissolved rocks and soils into a cocktail of metals, including chromium,” says Konhauser. “The minerals were then carried to the oceans by the run-off of rain water.

“Our examination of the ancient seabed data shows the chromium levels increased significantly
2.48 billion years ago,” said Konhauser. “This gives us a new date for the Great Oxidation Event, the time when the atmosphere first had oxygen.”

The rising levels of atmospheric oxygen fostered the development of new bacteria species, and Konhauser says that, following the evolutionary path back to that first oxygen-breathing life form on land, our ancestors started off in a pool of highly acidic water.

The researchers say the modern analogue for that first primitive oxygen-dependent life form on Earth is still with us.

“The same bacterial life forms are alive and well today, living off pyrite and settling in the highly acidic waste waters of mining sites the world over,” said Konhauser.

The research by Konhauser and his team is published in the Oct. 20 edition of the journal Nature.