Paleoexhibit

Theropods of the British Isles Part I

2012-02-29T09:08:00.002-08:00

The bipedal theropods represent the most diverse group of dinosaurs including all the meat-eating ones as well as some omnivorous and herbivorous forms. Primitive theropods include the coelophysoids (small, slender and lightly built dinosaurs that thrived worldwide during the Late Triassic, and for which the best known representative is the North American Coelophysis), the ceratosaurs (including forms such as Ceratosaurus and Carnotaurus) and the tetanurans. The last group contains the vast majority of the theropods and its members are characterized among other things by a rigid tail and the total loss of the fourth and fifth digits in their hands. Megalosaurs (i.e. Megalosaurus) are early tetanurans while Spinosaurs (i.e. Spinosaurus and co) are possibly related to them. Later tetanurans are the allosauroids (large predators such as Allosaurus and Carcharodontosaurus) and the coelurosaurians, which in turn include the tyrannosauroids (such as Tyrannosaurus), the ornithomimosaurs (the ostrich-mimic forms such as Struthiomimus and Ornithomimus) and the maniraptorans. The maniraptorans with their modified wrist and generally large hands are represented by the birds (where the hands became wings) and all their closest relatives, such as the oviraptosaurs (Oviraptor and co), the deinonychosaurs (Velociraptor and co).

Fig 1.- Small coelophysoids lived during the Late Triassic in Great Britain.

Late Triassic Theropods

During the Upper Carnian (~ 220 MYA) of Scotland lived Saltopus elginensis Huene 1910, known from a poorly preserved partial skeleton including dorsal, sacral and caudal vertebrae and fragments of fore and hind limbs (BMNH R3915) found in the Lossiemouth Sandstone Formation, near Elgin, Morayshire. The exact affinities of the animal have been debated. It was either a primitive theropod or a more ancestral dinosauriform.

Theropods were definitely present during the Late Triassic period in the British Isles as proven by the discovery of fragments in the fissure fills of southern Wales. A pelvis, femur and dorsal vertebrae (BMNH PV RU P77/1 and RUP 76/1) from Pant-y-ffynon, Wales of Norian age (~210 MYA), were possibly from a coelophysoid.

The dubious ‘Zanclodon’ cambrensis Newton, 1899 of Rhaetian age (~200 MYA) is known from the mold of a large left dentary with teeth (BGS 6532/BMNH R2912) from Glamorganshire, Wales (Lilstock Fm). This one might be another coelophysoid.

Fig 2.- Larger coelophysoid such as Sarcosaurus roamed the Early Jurassic of England.

Early Jurassic Theropods

In the early Jurassic, coelophysoids are represented by the shadowy Sarcosaurus. The type species, Sarcosaurus woodi Andrews, 1921 is known from a partial pelvis, femur and vertebra (BMNH 4840/1) from Leicestershire (Lias Fm) of Early Sinemurian age (which probably is actually of earlier Late Rhaetian or Hettangian age, ~198-200 MYA). A second species, Sarcosaurus andrewsi Huene, 1932 (= Magnosaurus woodwardi) is based on a partial right tibia (BMNH R3542), originally reported by Woodward in 1908 from Warwickshire of Hettangian age (~198 MYA). Sarcosaurus was a quite large coelophysoid with an estimated length of about 3.5 m.

From the Sinemurian (~192 MYA) Upper Broadford Beds Formation of the Isle of Skye (Scotland) came an incomplete right tibia (NMS.G.1994.10.1), interpreted as belonging to a small theropod, probably another coelophysoid (Benton et al., 1995).

A partial hindlimb from Charmouth, Dorset (BMNH 39496) that was described by Owen (1861) alongside remains of the ornithischian Scelidosaurus harrisonii was reported from the Lower Lias (Hettangian-Sinemurian). This one was found to be comparable to a megalosaur and would therefore be an early member of this group of large theropods that will dominate the Middle Jurassic period.

Finally, a tooth (BMNH 41352) from the Lias group of Lyme Regis, was named ‘Megalosaurus’ lydekkeri von Huene, 1926 (= Magnosaurus lydekkeri), is from an indeterminate theropod.

Original artworks on Paleoexhibit are copyrighted to Nobu Tamura. Do not use without permission (Email: nobu dot tamura at yahoo dot com)

References:

C. W. Andrews. 1921. On some remains of a theropodous dinosaur from the Lower Lias of Barrow-on-Soar. Annals and Magazine of Natural History, series 9 8:570-576

M.J. Benton, D.M. Martill & M.A. Taylor, 1995. The first Lower Jurassic dinosaur from Scotland: limb bone of a ceratosaur theropod from Skye. Scottish Journal of Geology, 31, 177–182.

F. v. Huene. 1910. Ein primitiver Dinosaurier aus der mittleren Trias von Elgin [A primitive dinosaur from the Middle Trias of Elgin]. Geologie und Paläontologie Abhandlungen (n.s.) 8(6):317-322.

D. Naish and D. M. Martill. 2007. Dinosaurs of Great Britain and the role of the Geological Society of London in their discovery: basal Dinosauria and Saurischia. Journal of the Geological Society, London 164:493-510.

O. W. M. Rauhut and A. Hungerbühler. 2000. A review of European Triassic theropods. GAIA 15:75-88.

Sauropods of the British Isles Part III

2012-02-18T08:36:00.000-08:00

Fig 1.- Rebbachisaurids were present on the Isle of Wight during the Early Cretaceous.

Sauropods from the Early Cretaceous (part II)

The Wessex Formation of the Isle of Wight

The Wessex formation on the Isle of Wight of Barremian age (~ 127 MYA) has a number of sauropod remains, all very fragmentary but enough to point to a high degree of diversity for this group in the British Isles during the Early Cretaceous.

The presence of Diplodocids is scarce if ever they were present at all. A chevron has been described by Alan Charig (1980) as belonging to a diplodocid, but the identification has since then been disputed. The presence of Rebbachisaurids, on the other hand, is well attested and is represented by isolated bones, including a characteristic scapula [= shoulder blade] (MIWG 6544), tail vertebra (MIWG 5384) and possibly teeth. From these scant remains, it appears that the unnamed British representative of this group is most closely related to the Spanish Demandasaurus and the African Nigersaurus (see my previous post about it).

Brachiosaurids were also certainly there and remains are represented by ‘Pleurocoelus’ valdensis Lydekker, 1889, based on teeth, dorsal and caudal vertebra found near Cuckfield, East Sussex, Hastings beds and on the Isle of Wight. Usually considered to be dubious, Pleurocoelus valdensis is, according to Ruiz-Omeñaca & Canudo (2005), a perfectly valid taxon that was also present in the Iberian Peninsula. Other possible brachiosaurid remains include ‘Ornithopsis’ eucamerotus Hulke, 1882, based on a set of pelvis bones (BMNH R97), an unnamed taxon evidenced by a single large cervical vertebra (MIWG 7306) that might have belonged to the largest dinosaur of Europe (Naish et al., 2004), and Eucamerotus foxi Blows, 1995, described from a neural arch (BMNH R2522), two dorsals (BMNH R89-90) and another dorsal from a juvenile specimen (BMNH R2524). Oplosaurus armatus Gervais, 1852, is based on a large tooth (BMNH R964) that may belong to a brachiosaurid, but more recent analysis indicated it is more probably from a camarasaurid (Canudo et al., 2002). Chondrosteosaurus gigas Owen, 1876 is known from two neck vertebrae (BMNH 46869 & BMNH 46870) and is probably a basal titanosauriform, although we cannot say if it is a camarasaurid or a brachiosaurid.

Fig 2.- The specialized Titanosaurs were the dominant group of sauropods at the end of the Early Cretaceous.

The most evolved group of sauropods, the titanosaurs, is represented by Iuticosaurus valdensis LeLoeuff et al., 1993, known from 2 tail vertebrae (BMNH R146a & BMNH 151).

Finally, two dubious taxa are indeterminate sauropods: the Isle of Wight ‘Ornithopsis’ hulkei dorsal vertebra (BMNH R28632) was renamed Bothriospondylus elongatus by Owen in 1875 and ‘Ornithopsis’ eucamerotus by Hulke in 1882. Chondrosteosaurus magnus Owen, 1876 is based on a single partial vertebra (BMNH R98).

The Lower and Upper Greensand

The Lower Greensand Group of Aptian age (~120 MYA) delivered a pelvis and associated sacrum (BMNH R12713) from Luccombe Chine, Isle of Wight of a titanosauriform of some sort (Stroh, 1949, Blows, 1995). Also from the Lower Greensand came Dinodocus mackesoni Owen, 1884, based on a humerus (BMNH 14695) from Hythe, Kent. Possibly another indeterminate titanosauriform.

The Upper Greensand formation (Albian-Cenomanian age, ~112 MYA) in southeastern England bears a few sauropod remains, which are the youngest in the British Isles and all belong to titanosaurs. “Titanosaurus” lydekkeri Huene, 1929 (= Iuticosaurus lydekkeri), based on a vertebra (BMNH 32390) found on the Isle of Wight, was synonymized with Macrurosaurus semnus by McIntosh, 1990, but generally considered a nomen dubium. Macrurosaurus semnus Seeley, 1876 is based on a set of 25 caudal vertebrae (SM B55630) and 15 more various bits found in Cambridgeshire and of Cenomanian age, and is an indeterminate titanosaur.

This concludes our tour of the sauropods of the British Isles.

Original artworks on Paleoexhibit are copyrighted to Nobu Tamura. Do not use without permission (Email: nobu dot tamura at yahoo dot com)

References:

W. T. Blows. 1995. The Early Cretaceous brachiosaurid dinosaurs Ornithopsis and Eucamerotus from the Isle of Wight, England. Palaeontology 38(1):187-197

W. T. Blows. 1998. A review of Lower and Middle Cretaceous dinosaurs of England. In S. G. Lucas, J. I. Kirkland, and J. W. Estep (eds.), Lower and Middle Cretaceous Terrestrial Ecosystems, New Mexico Museum of Natural History and Science Bulletin 14:29-38

J. Le Loeuff, E. Buffetaut, M. Martin, V. Martin, and H. Tong. 1993. Découverte d'Hadrosauridae (Dinosauria, Ornithischia) dans le Maastrichtian des Corbières (Aude, France) [Discovery of Hadrosauridae (Dinosauria, Ornithischia) in the Maastrichtian of Corbières (Aude, France)]. Comptes Rendus de l'Academie des Sciences, Paris, Série II 316:1023-1029

R. Lydekker. 1889. Note on some points in the nomenclature of fossil reptiles and amphibians, with preliminary notices of two new species. Geological Magazine, decade 3 6:325-326

R. Lydekker. 1893. On a sauropodous dinosaurian vertebra from the Wealden of Hastings. Quarterly Journal of the Geological Society of London 49:276-280

J. S. McIntosh. 1990. Sauropoda. In D. B. Weishampel, H. Osmólska, and P. Dodson (eds.), The Dinosauria. University of California Press, Berkeley 345-401

A. G. Melville. 1849. Notes on the vertebral column of the Iguanodon. Philosophical Transactions of the Royal Society of London 139:285-300.

D. Naish, D.M. Martill, D. Cooper & K.A. Stevens, 2004. Europe’s largest dinosaur? A giant brachiosaurid cervical vertebra from the Wessex Formation (Early Cretaceous) of southern England. Cretaceous Research, 25, 787–795.

D. Naish and D. M. Martill. 2007. Dinosaurs of Great Britain and the role of the Geological Society of London in their discovery: basal Dinosauria and Saurischia. Journal of the Geological Society, London 164:493-510

R. Owen. 1876. Monograph on the fossil Reptilia of the Wealden and Purbeck formations. Supplement no. VII. Crocodilia (Poikilopleuron) and Dinosauria? (Chondrosteosaurus). [Wealden.]. The Palaeontographical Society, London 1876:1-7

J. I. Ruiz-Omeñaca and J. I. Canudo. 2005. "Pleurocoelus" valdensis Lydekker 1889 (Saurischia, Sauropoda) en el Cretácico Inferior (Barremiense) de la Península Ibérica ["Pleurocoelus" valdensis Lydekker 1889 (Saurischia, Sauropoda) in the Lower Cretaceous (Barremian) of the Iberian Peninsula]. Geogaceta 38:43-45

H. G. Seeley. 1870. On Ornithopsis, a gigantic animal of the pterodactyle kind from the Wealden. Annals and Magazine of Natural History, series 4 5:279-283.

H. G. Seeley. 1876. On Macrurosaurus semnus (Seeley), a long tailed animal with procoelous vertebrae from the Cambridge Upper Greensand, preserved in the Woodwardian Museum of the University of Cambridge. Quarterly Journal of the Geological Society of London 32:440-444

M. P. Taylor and D. Naish. 2007. An unusual new neosauropod dinosaur from the Lower Cretaceous Hastings Beds Group of East Sussex, England. Palaeontology 50(6):1547-1564.

Sauropods of the British Isles Part II

2012-02-09T09:02:00.000-08:00

Fig 1.- A hypothetical reconstruction of Pelorosaurus conybeari.

Sauropods from the Early Cretaceous (I)

The Hastings Beds

The Hastings Beds in East Sussex, of Berriasian-Valanginian age (~140 MYA), bore a number of fragmentary sauropod remains. A set of tail vertebrae and chevrons (BMNH R2544–2555) found near Cuckfield, East Sussex, were originally described alongside some iguanodont remains by Richard Owen as Cetiosaurus brevis (Owen, 1842). Alexander Melville, noting Owen’s mistake, renamed the sauropod vertebrae Cetiosaurus conybeari (Melville, 1849). A year later, Gideon Mantell realizing that they belong to a animal quite distinct from Cetiosaurus, changed the name into Pelorosaurus conybeari (Mantell, 1850), and added to the description, a humerus (BMNH 28626) found a few meters away from the original vertebrae material. This succession of attribution changes resulted in a taxonomical nightmare for the later generation scientists. Technically, the name C. brevis has indeed seniority over Pelorosaurus conybeari and should be considered to be the valid name. However, with the invalidation of C. medius (see Part I), C. brevis would also be the type species of the genus Cetiosaurus, making its use for the Middle Jurassic C. oxoniensis, which turned out to be a very different animal quite problematic (As far as I know, the petition to ICZN to make C. oxoniensis the type species of Cetiosaurus is still pending) . As for the general aspect of what Pelorosaurus may have looked like, all that can be said from the scant remains is that it was a brachiosaurid and would probably resemble to a smaller version of the North American Late Jurassic Brachiosaurus, with a possible size of some 15 meters in length.

Not much can be said about the three other named sauropods of the Hastings Beds. ‘Pelorosaurus’ becklesi Mantell, 1852 (= Morosaurus becklesii Marsh, 1889) based on a humerus (BMNH R1868), ulna, radius and skin impressions, probably belong to a different animal than Pelorosaurus conybeari. It may also be a brachiosaurid unless it is a more advanced titanosaur. ‘Ornithopsis’ hulkei Seeley, 1870 is based on two dorsal vertebrae, one from East Sussex (BMNH R2239), the other from the Isle of Wight Wessex Formation (BMNH R28632), and originally thought to belong to a pterosaur (thus the genus name which means “bird likeness”). Owen (1876), however, split the two findings, naming the East Sussex vertebrae Bothriospondylus magnus, then Chondrosteosaurus magnus. The remains have no distinct characteristics apart the fact that they belong to a sauropod of some sort so the name should be considered dubious. Xenoposeidon proneneukos Taylor & Naish, 2007 is based on a single partial back vertebra (BMNH R2095). Xenoposeidon’s vertebra is so unique that its affinities within the Sauropods are quite uncertain.

Next will be the sauropods from the Wessex Formation.

Original artworks on Paleoexhibit are copyrighted to Nobu Tamura. Do not use without permission (Email: nobu dot tamura at yahoo dot com)

References:

G. A. Mantell. 1850. On the Pelorosaurus; an undescribed gigantic terrestrial reptile, whose remains are associated with those of Iguanodon and other saurians in the strata of the Tilgate Forest, in Sussex. Philosophical Transactions of the Royal Society of London 140(16):379-390.

A. G. Melville. 1849. Notes on the vertebral column of the Iguanodon. Philosophical Transactions of the Royal Society of London 139:285-300.

D. Naish and D. M. Martill. 2007. Dinosaurs of Great Britain and the role of the Geological Society of London in their discovery: basal Dinosauria and Saurischia. Journal of the Geological Society, London 164:493-510.

R. Owen. 1876. Monograph on the fossil Reptilia of the Wealden and Purbeck formations. Supplement no. VII. Crocodilia (Poikilopleuron) and Dinosauria? (Chondrosteosaurus). [Wealden.]. The Palaeontographical Society, London 1876:1-7.

H. G. Seeley. 1870. On Ornithopsis, a gigantic animal of the pterodactyle kind from the Wealden. Annals and Magazine of Natural History, series 4 5:279-283.

M. P. Taylor and D. Naish. 2007. An unusual new neosauropod dinosaur from the Lower Cretaceous Hastings Beds Group of East Sussex, England. Palaeontology 50(6):1547-1564.

Sauropods of the British Isles I

2012-01-29T19:06:00.000-08:00

Fig 1.- Reconstruction of Cetiosaurus oxoniensis.

Sauropods, the long-necked, long-tailed giant herbivorous dinosaurs, are better known in popular imagination by their North American representatives, Diplodocus and Brachiosaurus. Sauropods are divided into a number of families and groups that can be distinguished from details of their skeletal anatomy and teeth. Among the most primitive families, the Melanosaurids were only recently (Yates, 2007) recognized as early sauropods instead of being placed within more basal sauropodomorphs. Cetiosaurids are an ill-defined group of primitive sauropods built around the British Cetiosaurus and perhaps including other members such as the Chinese club-tailed Shunosaurus. The Turiasaurs form a recently erected clad (Royo-Torres et al., 2006) of gigantic sauropods so far restricted to southernwestern Europe. The Diplodocoids regroup three distinct families, the highly specialized rebbachisaurids, the relatively short-necked, tall-spined dicraeosaurids and the long and slender diplodocids. The Macronarians are characterized by their erect neck posture and comparatively large nasal opening (nostrils) on their head. They are subdivided into the camarasaurids (primitive macronarians), brachiosaurids and titanosaurs, the last two families including the largest and heaviest creatures that ever walked the earth.

Numerous remains of sauropods were found in the British Isles, but the vast majority of the named genera and species are based on very scant material with no unique characteristics making them nomina dubia (dubious names). However, they can generally be diagnosed at higher group levels, showing that the British Isles were once home to a diverse fauna of sauropods that include the earliest members of such groups as the Diplodocoidea and Rebbachisauridae. Let’s meet them in stratigraphical chronological order (please note that the list of fossils mentioned is in no way exhaustive)...

We already met in a previous post, Camelotia borealis from the Westbury Formation of Late Triassic Rhaetian age, which was possibly an early sauropod, unless it is a large representative of something more basal.

Sauropods from the Middle Jurassic

The first definite British sauropod remain comes from the Middle Jurassic Aalenian stage (~175 MYA). It consists of a partial left pubis and ischium (BMNH R9472) of the Northampton Sands Formation, from Harleston, Northamptonshire (Reid, 1984). This unnamed taxon was possibly a brachiosaurid or a titanosaur making it either way the earliest recorded macronarian in the world.

Fig 2.- Britain has some remains belonging to the earliest known macronarian.

Next come large collection of bones from the Forest Marble Formation of Bathonian age (~165 MYA). The most famous fossil of this formation is the primitive sauropod Cetiosaurus (“whale lizard”). Cetiosaurus is one of the earliest dinosaurs to receive a name and, as it happened to many genera described in the early days of paleontology, it became a so-called wastebasket taxon, with up to 13 species described in the British Isles alone, ranging temporally from the Middle Jurassic to the Early Cretaceous. In a general revision of the genus, Upchurch and Martin (2003) finally recognized the only Cetiosaurus oxoniensis Phillips, 1871 from the Forest Marble as a valid species. Cetiosaurus is known from various postcranial elements coming from different places in Oxfordshire (OUM J13605-13613, 13615-13616, 13619-13688, 13899), Northamptonshire and Gloucestershire. A partial skeleton from the slightly older Bajocian (~ 170 MYA) Rutland Formation of Rutland (LCM G468.1968) is also being assigned to C. oxoniensis, as well as a partial braincase (OUM J13596) and a tooth (OUM J13597) found at the same location than the Oxfordshire Blechington specimen. This large, perhaps 20 meters long sauropod exhibits a number of primitive features in the structure of their vertebrae. Due to the fragmentary nature of the remains, many aspects of this animal, such as the skull, are almost totally unknown, despite it being the best-known sauropod of Great Britain.

Cetiosaurus medius Owen, 1842 known from 11 caudal centra (OUM J13693–13703) and other various bits found in Oxfordshire, Gloucestershire, Buckinghamshire, is non-diagnostic. Since C. medius is generally considered as the type species of Cetiosaurus, its invalidation would render the naming of C. oxoniensis problematic. A petition has therefore been filed to ICZN to make C. oxoniensis the new type species for the genus. Cardiodon rugulosus described by Owen in 1844, out of a single, now lost, tooth unearthed near Bradford-on-Avon, Wiltshire, may be the same animal than Cetiosaurus, but it was also been proposed to be a Turiasaur.

Two other distinct taxa are known from the Forest Marble Formation: one is ‘Cetiosaurus’ glymptonensis Phillips, 1871 (= Cetiosauriscus glymptonensis (Phillips, 1871) McIntosh, 1990) described from a series of 9 caudal vertebrae (OUM J13750-13758) found in Glympton, Oxfordshire. It was possibly a diplodocoid, making it the earliest known member of this group in the world. However, due to the lack of unique characters, C. glymptonensis is generally considered to be a nomen dubium (Barrett et al., 2003). The as dubious Bothriospondylus robustus Owen, 1875 = Marmarospondylus robustus) from Bradford-on-Avon, Wiltshire, is known from a single dorsal vertebra (BMNH R22428) and might be a macronarian.

Another possible macronarian has been described from the similar age Kilmaluag Formation (late Bathonian) of Strathaird, Isle of Skye, Western Scotland: it is a tooth (NMS G 2004.31.1), one of the very rare dinosaurian remains found in Scotland. This fossil is distinctly different from both Cetiosaurus and Cardiodon (Barrett, 2006).

From the Lower Callovian age (~163 MYA) Kellaways formation, comes ‘Ornithopsis’ leedsi Hulke, 1887, known from vertebrae, ribs and pelvic fragments (BMNH R1984-1988), found near Peterborough, Cambridgeshire. This was probably a Brachiosaurid. The name Ornithopsis originally refers to the undeterminate O. hulkei from the Early Cretaceous (see part II), which would mean that O. leedsi probably requires a new generic name.

Fig 3.- other remains from britain are from the earliest known diplodocoid.

In the overlying Oxford Clay Formation (Middle Callovian – Early Oxfordian age, ~161 MYA), other materials from Peterborough, including a series of vertebrae (BMNH R.3078) were confusingly also referred to ‘Ornithopsis’ leedsi by Woodward in 1905. But Charig concluded in 1980 that the bones belong to a quite different animal, a diplodocid, and give them the name ‘Cetiosauriscus’ stewarti.

Sauropods from the Late Jurassic

From the Kimmeridge Clay Formation of Kimmeridgian age (~153 MYA), comes Duriatitan humerocristatus (Lydekker, 1888) (Initially named 'Cetiosaurus' humerocristatus) based on a gracile left humerous (BMNH R44635) from Weymouth, Dorset (Hulke, 1874). It was determined to belong to a Titanosauriform (Barrett et al., 2010). The dubious ‘Ornithopsis’ manseli (Lydekker, 1888) (= ‘Ischysaurus’ manseli ), based on a partial humerus ((BMNH 41626), also from Dorset, may belong to the same animal. The same can be said of Bothriospondylus suffosus Owen, 1875 from Wiltshire, known from dorsal and sacral vertebrae (BMNH R44592-5: 4).

Some non-diagnostic vertebrae, limb elements and dermal scutes found near Stretham, Cambridgeshire (BMNH 32498-99) were described as Gigantosaurus megalonyx Seeley, 1869 and belong to a sauropod of some sort. Also from the Kimmeridgian, ‘Cetiosaurus’ longus Owen, 1842 based on a single dorsal and caudal centra (OUM J13617) from the Portland Stone Formation at Garsington, Oxfordshire, is an indeterminate sauropod.

Original artworks on Paleoexhibit are copyrighted to Nobu Tamura. Do not use without permission (Email: nobu dot tamura at yahoo dot com)

References:

P. M. Barrett. 2006. A sauropod dinosaur tooth from the Middle Jurassic of Skye, Scotland. Transactions of the Royal Society of Edinburgh: Earth Sciences 97:25-29

P. M. Barrett, R. B. J. Benson, and P. Upchurch. 2010. Dinosaurs of Dorset: Part II, the sauropod dinosaurs (Saurischia, Sauropoda) with additional comments of the theropods. Proceedings of the Dorset Natural History and Archaeological Society 131:113-126

A. J. Charig. 1980. A diplodocid sauropod from the Lower Cretaceous of England. In L. L. Jacobs (ed.), Aspects of Vertebrate History: Essays in Honor of Edwin Harris Colbert. Museum of Northern Arizona Press, Flagstaff 231-244

J. W. Hulke. 1874. Note on a very large saurian limb-bone adapted for progression upon land, from the Kimmeridge Clay of Weymouth, Dorset. Quarterly Journal of the Geological Society of London 30:16-17

D. Naish and D. M. Martill. 2007. Dinosaurs of Great Britain and the role of the Geological Society of London in their discovery: basal Dinosauria and Saurischia. Journal of the Geological Society, London 164:493-510

R. Owen. 1841. Description of a portion of the skeleton of the Cetiosaurus, a gigantic extinct saurian reptile occurring in the Oolitic formations of different portions of England. Proceedings of the Geological Society of London 3, part 2(80):457-462

R. Owen. 1875. Monographs on the fossil Reptilia of the Mesozoic formations. Part II. (Genera Bothriospondylus, Cetiosaurus, Omosaurus). The Palaeontographical Society, London 1875:15-93

M. D. Jones. 1970. Cetiosaurus oxoniensis, Phillips J. A middle Jurassic sauropod from Rutland, England. Leicester Literary and Philosophical Society 64:144-150

J. Phillips. 1871. Geology of Oxford and the Valley of the Thames. Clarendon Press, Oxford 1-523.

P. M. Upchurch and J. Martin. 2003. The anatomy and taxonomy of Cetiosaurus (Saurischia, Sauropoda) from the Middle Jurassic of England. Journal of Vertebrate Paleontology 23(1):208-231.

Spinops: my very own personal paleoart portfolio

2012-01-29T17:13:00.000-08:00

Once upon a while, scientists came with really catchy dinosaur names. Examples of cool generic nomina include Dracorex (the “dragon king”), Raptorex (the “king thief”), Cryptoraptor (the “hidden thief”), Brontosaurus (the “thunder lizard”) and Diabloceratops (the “devil horn face”). Shame that some of those critters turn out to be invalid and too bad scientific names cannot be recycled! Others are just plain awful. For (at least) English speakers, there are real tongue twisters such as Bruhatkayosaurus (fortunately this one might just be a hoax [great post from Matt Martyniuk]), Futalognkosaurus (do I even get the spelling right?), Krzyzanowskisaurus, Naashoibitosaurus.

Among the recently allocated names, Spinops is one of the best I came across: it is short, easy to remember and combines those of two of the most iconic dinosaurs, Spinosaurus and Triceratops. Good reasons to use it for my new paleoart portfolio website, before somebody else get the same idea…

I’ve just started, and so far it has only some 140 images in it as I have to go through all my folders and hard drives to check what I've done since 2007. The nice thing about this online portfolio is that it is wholly searchable (type for instance “plesiosaur” if you want to see these only), and illustrations can be arranged by group or production date. Have a look…

Late Triassic Dinosaurs of the British Isles

2012-01-08T17:39:00.000-08:00

Fig 1.- Thecodontosaurus antiquus.

The British Late Triassic land vertebrate fauna is essentially known from disarticulated bones found in various Mesozoic fissure fills of underlying Lower Carboniferous limestone in England and Wales. The fauna include the very first British dinosaurs of Rhaetian age (~ 200 MYA), living alongside a variety of reptiles including sphenodontians, running crocs of the sphenosuchian group (such as Terrestrisuchus gracilis), trilophosaurs (such as Variodens inopinatus), and gliding lizards such as Kuhneosaurus. Dinosaurs were not the dominant group that will rule the land during the Jurassic and Cretaceous periods, constituting only about 10% of the vertebrate fauna found in those fissure fills. One archosaurian form, named Agnostiphys cromhallensis from the Cromhall Quarry in Avon, has clearly some dinosaurian characteristics. It was described in 2002 by N.C. Fraser and co-workers based on a left ilium, left maxilla, a right humerus, a pair of astragalus and an isolated tooth. The validity of the taxon is disputed as the different parts may come from different animals (thus making the original description a chimera) and the remains are too scant to decide if it was an archosaur closely related to dinosaurs or a true primitive dinosaur, possibly a herrerasaur.

Sauropodomorphs from Rhaetian fissure fills: Thecodontosaurus, Asylosaurus, Pantydraco

The other dinosaurian remains of the Rhaetian fissure fillings all belong to basal sauropodomorphs, the group of saurischian dinosaurs which will eventually lead to the Jurassic and Cretaceous long-necked herbivorous giants called Sauropods to which the North American Brachiosaurus, Diplodocus and Apatosaurus are the most popular members. From a locality known as Durdham Down, Clifton, near Bristol in England, hundreds of bones have been excavated in the 1830s and originally described by Riley and Stutchbury as three separate taxa: Thecodontosaurus antiquus based on a right dentary with 21 teeth, Paleosaurus cylindricon (Now Paleosauriscus cylindicon) and P. platyodon (now Rileyasuchus platyodon), the latter two, each based on a single tooth. The other bones were subsequently distributed by Owen (1842), Huxley (1870) and Marsh (1892) among the three taxa. Huxley (1870) was the first to recognize the dinosaurian nature of the remains. The different disarticulated bits had subsequently quite diverging and complicated systematic histories, some being referred to a phytosaur (i.e. Rileya), others to theropods and ornithosuchians. Sadly, a portion of the materials, including the holotype dentary of Thecodontosaurus, was destroyed during the WWII bombing of Bristol. Recent efforts try to put order in the systematic mess accumulated over more than a century, but opinions went from attributing all the Durdham Down dinosaurian bones to the single species of basal sauropodomorph, Thecodontosaurus antiquus (Benton et al., 2000) with different morphotypes representing sexual dimorphism, to reserving the generic name to the original jaw and its neotype only (Galton, 2005). In his last magisterial review, Pete Galton (2007) examined all the surviving materials of Durdham Down (including the mislabeled bones which were for a while thought to come from Australia, leading Seeley to described them in 1861 as a new species, Agrosaurus macgillivray, which would have been the earliest known dino from down under) and illustrations made of materials lost during the war. He concluded that the Durdham Down collection is a mixture originating from a handful of species: Thecodontosaurus antiquus, to which the jaw and gracile bones were attributed, a new erected taxon, Asylosaurus yalensis for the only significant articulated skeletal part (an almost complete forearm and associated dorsal vertebrae and ribs), and a few number of unnamed basal sauropodomorphs, including a possible anchisaur. New materials of Thecodontosaurus have been discovered in fissure fill at Tytherington Quarry, Avon, in 1975 are are being prepared and awaiting formal description. Compared to the later huge sauropods, Thecodontosaurus was a rather small dinosaur measuring no longer than 2.5 meters in length that was probably bipedal. His leaf shaped teeth indicated that it was a herbivore.

Fig 2.- Pantydraco caducus.

From the more or less contemporary fissures fill of Panty-ffynnon Quarry in South-Western Wales, came several partial skeletons including an almost complete skull and associated partial skeleton of the unfortunately named Pantydraco caducus. The remains are from a juvenile basal sauropodomorph. Like Thecodontosaurus, Pantydraco was a bipedal herbivore, measuring probably no more than 2 meters in length.

Fig 3.- Camelotia borealis.

The large Late Triassic sauropodomorph, Camelotia

All the sauropodomorphs from the rhaetian fissure fills were rather small in size and gracile in appearance, but a larger animal announcing the heavy sauropods from the Jurassic, existed at that time, as proven by a partial disarticulated skeleton found in sedimentary beds at the base of the Westbury formation at Wedmore Hill, Somerset. The animal was named Camelotia borealis, after the legendary castle of King Arthur. Remains of Camelotia are so fragmentary that it is hard to derive its affinities but it might have been related to the quadrupedal Melanosaurus, unless it was a very primitive sauropod. Camelotia is estimated to have measured about 10 meters in length.

Original artworks on Paleoexhibit are copyrighted to Nobu Tamura. Do not use without permission (Email: nobu dot tamura at yahoo dot com)

References:

Benton M.J. , Juul, L., Storrs, G.W. & Galton, P. M. 2000. Anatomy and systematics of the prosauropod dinosaur Thecodontosaurus antiquus from the Upper Triassic of Southwest England. Journal of Vertebrate Paleontology 20: 77–108.

Fraser, N. C., K. Padian, G. M. Walkden, & A.L.M. Davis , 2002. Basal dinosauriform remains from Britain and the diagnosis of the Dinosauria. Palaeontology , 45 (1): 79-95.

Galton. P. M. 2005. Basal sauropodomorph dinosaur taxa Thecodontosaurus Riley & Stutchbury, 1836, T. antiquus Morris, 1843 and T. caducus Yates, 2003: their status re: humeral morphs from the 1834 fissure fill (Upper Triassic) in Clifton, Bristol, UK. Journal of Vertebrate Paleontology 25(3, suppl.):61A

Galton, P. M. 2007. Notes on the remains of archosaurian reptiles, mostly basal sauropodomorph dinosaurs, from the 1834 fissure fill (Rhaetian, Upper Triassic) at Clifton in Bristol, southwest England. Revue de Paléobiologie 26(2):505-591.

Galton, P. M., Yates, A. M. and Kermack, D. M. 2007. Pantydraco n. gen. for Thecodontosaurus caducus Yates, 2003, a basal sauropodomorph dinosaur from the Upper Triassic or Lower Jurassic of South Wales, UK. Neues Jahrbuch für Geologie und Paläontologie Abhandlungen 243(1):119-125.

Naish, D. and Martill., D. M. 2007. Dinosaurs of Great Britain and the role of the Geological Society of London in their discovery: basal Dinosauria and Saurischia. Journal of the Geological Society, London 164:493-510

Yates. A.M. 2003. A new species of the primitive dinosaur Thecodontosaurus (Saurischia: Sauropodomorpha) and its implications for the systematics of early dinosaurs. Journal of Systematic Palaeontology 1(1):1-42.

R.I.P. Dan Varner (April 19, 1949 - January 1, 2012)

2012-01-04T20:01:00.000-08:00

Mosasaurus by Dan Varner.

I did not have the privilege to know Dan Varner and did not know until very recently, shame on me, that he was the man behind the beautiful paintings illustrating the “Oceans of Kansas” website. I sadly learned that he passed away on January 1st, 2012 after a prolonged battle with illness; a tremendous loss for the entire paleoart community…

From all the amazing Mesozoic marine life depictions he created during his too short a career, this one is a personal favorite. Mosasaurs were after all closely related to the modern monitor lizards, so it makes perfect sense to give them a similar tongue! The underwater light effect is eye-catching and the three transfixed ammonites watching the marine lizard swimming by gives to the entire scene a unique sense of cephalopodian apprehension... simply beautiful!

It’s hardly my place, I think, for me, an amateur nobody, to give a fitting eulogy to such a great artist so I am simply directing you to the ‘in memoriam’ sections I came across on the web, starting with the “Oceans of Kansas” website, followed by tributes from paleo-illustrators Jaime Headden (check his Globidens), Matt van Roojien, David Maas and from the Art Evolved Crew.

Ankylosaurs of the British Isles

2012-01-02T11:42:00.000-08:00

Fig 1.- Hyleosaurus armatus.

The Ankylosaurs form a group of heavily armored ornithischian dinosaurs best known by its North American cretaceous representatives, Ankylosaurus and Euoplocephalus. Ankylosaurs and Stegosaurs together form the Thyreophorans characterized by a body covered with an armor consisting of scutes, spikes and plates, that are highly derived osteoderms (ossified scales commonly found in various groups of vertebrates such as the crocodilians).

The Ankylosaurs are divided into two or three families. The Nodosaurids have a narrow skull, a club-less tail and large spikes while the Ankylosaurids have a distinct bony club at the end of their tails and a wider body. In addition, some authors detach some Nodosaurids, into a third family, the more lightly built Polacanthids.

Scelidosaurus harrisonii from the Early Jurassic of Dorset, is an early thyreophoran close to the ancestral stock of both stegosaurs and ankylosaurs. There is however a large gap in the fossil record between the first definite ankylosaur in the United Kingdom and Scelidosaurus. Jurassic ankylosaur remains are so fragmentary that not much definite can be said about them.

In the Middle Jurassic (Bajocian, 170 MYA), an incomplete radius and ulna (forearm bones) from the Isle of Skye in Scotland, described by Clark in 2001, possibly belongs to an ankylosaur, unless it is a stegosaur.

A bit younger (Middle Jurassic, Callovian, 163 MYA), Sarcolestes leedsi is known from an incomplete lower jaw from the Oxford Clay Formation in Cambridgeshire. Three osteoderms recovered from the same formation have been attributed to it (Galton, 1994). It was originally thought to be a theropod (thus its name meaning “flesh robber”), before being classified as a stegosaur, then an ankylosaur of some sort.

From the Late Jurassic period (Oxfordian, 160 MYA), a right femur found in the Ampthill Clay Formation of Cambridgeshire was named Cryptosaurus eumerus and first attributed to an ornithopod, until Peter Galton placed it among the ankylosaurs (1983). A maxilla of the same age named Priodontognathus phillipsi was found in Yorkshire. This also was first attributed to an ornithopod before Galton classified it as a nodosaurid ankylosaur (1980).

Better ankylosaur material appears in the Early Cretaceous with Hylaeosaurus and Polacanthus. Hylaeosaurus armatus is one of the original three animals (the others being Iguanodon and Megalosaurus) used by Sir Richard Owen to define the then new group he called Dinosauria in 1842. This 6 meter long polacanthid nodosaur is known from the Turnbridge Wells Sand Formation (Grinstead Clay member) of Valanginian age (~138 MYA) and its remains have been discovered in West Sussex. The holotype found in the Tilgate Forest area by Gideon Mantell in 1832 consists of the anterior portion of an articulated skeleton including a small portion of the skull. A second specimen from Bolney was partially destroyed by workers before Mantell could salvage a few bits including a left scapula, a fragment of the right scapula and a left tibia. A third specimen found by Mantell in 1827 from the Tilgate Forest quarry consists of an incomplete caudal series with armor (originally named H. oweni). From Mantell’s Bolney material combined with remains found in the Isle of Wight, Nopsca erected the new genus and species Polacanthoides ponderosus in 1928. Today, the Bolney material is attributed to Hylaeosaurus armatus while the Isle of Wight material is considered to belong to Polacanthus foxii, making Polacanthoides an invalid name. Hylaeosaurus is still a quite obscure animal despite being one of the earliest described dinosaurs. It was probably closely related to Polacanthus.

Fig 2.- Polacanthus foxii.

Polacanthus foxii, which was for some times being considered to be the same animal as Hylaeosaurus, is nowadays generally thought to be distinct. Stratigraphically, it is slightly younger, appearing only in the Wessex and Vectis Formations of the Isle of Wight of Upper Barremian age (~ 125 MYA). The generic name appears first in a anonymous field note from 1865 attributing the paternity of the name to Richard Owen. The holotype collected by the reverend William Fox consists of the rear end of the animal. A second specimen described by W. T. Blows in 1979 consists of neck vertebrae and anterior armor. A third specimen is currently in private ownership. A portion of a pelvis and some dermal armor, originally named Polacanthus becklesi by Hennig in 1924 is now considered to belong to P. foxii. Many other various bits attributed to P. foxii have been found including the now lost Isle of Wight parts used to define Polacanthoides ponderosus described above and the single spine named Vectensia by Delair, 1982. Polacanthus foxii was a 4-5 meter long nodosaur, serving as the type to the polacanthid family.

Blows has erected a second species of Polacanthus, P. rudgwickensis, in 1996 out of a partial skeleton from the mainland found near Rudgwick, Sussex. This species appears to be slightly larger and more robust than P. foxii but its validity has been disputed.

Fig 3.- Anoplosaurus curtonotus.

From the mainland Upper Greensand Formation of Albian age (~110 MYA), a number of fragments were attributed to ankylosaurs and named into several genera including Anoplosaurus, Acanthopholis, Eucercosaurus, Syngonosaurus and Macrurosaurus and a plethora of species. All of them, save perhaps Anoplosaurus curtonotus are dubious in the sense that from such fragmentary remains there are no unique characters to define each of the species. Anoplosaurus curtonotus has been described from various fragments from a juvenile individual and probably belong to a nodosaurid of some sort. The second species, A. major is probably chimeric. The genus Acanthopholis was often illustrated in dinosaur books but all the 7-9 species described, including the type A. horrida, were determined to be dubious by a review by Pereda-Superbiola and Barrett (1999).

This concludes our tour of the British Isles Ornithischians. Now to the Saurischians.

Original artworks on Paleoexhibit are copyrighted to Nobu Tamura. Do not use without permission (Email: nobu dot tamura at yahoo dot com).

References:

Blows, W. T. 1982. A preliminary account of a new specimen of Polacanthus foxi (Ankylosauria, Reptilia) from the Wealden of the Isle of Wight. Proceedings of the Isle of Wight Natural History and Archaeological Society 1980 pt. 5(7):303-306.

Clark, N.D.L. 2001. A thyreophoran dinosaur from the early Bajocian (Middle Jurassic) of the Isle of Skye, Scotland. Scottish Journal of Geology, 37, 19–26.

Fox. W. 1866. On a new Wealden saurian named Polacanthus. Report of the British Association for the Advancement of Science, Birmingham 1865:56.

Fox. W.1866. Another new Wealden reptile. Geological Magazine 3:383.

Galton, P.M. 1980. Priodontognathus phillipsii (Seeley), an ankylosaurian dinosaur from the Upper Jurassic (or possibly Lower Cretaceous) of England. Neues Jahrbuch für Geologie und Paläontologie Monatshefte 1980(8):477-489.

Galton, P.M. 1983. Armored dinosaurs (Ornithischia: Ankylosauria) from the Middle and Upper Jurassic of Europe, Palaeontographica Abteilung A 182(1-3): 1-25.

Galton, P. M. 1994. Dermal scutes of Sarcolestes, an ankylosaurian dinosaur from the Middle Jurassic of England. Neues Jahrbuch für Geologie und Paläontologie Monatshefte 1994(12):726-732

Naish, D.; and Martill, D. M. 2008. Dinosaurs of Great Britain and the role of the Geological Society of London in their discovery: Ornithischia. Journal of the Geological Society, London 165 (3): 613–623.

Pereda-Suberbiola, J. 1993. Hylaeosaurus, Polacanthus, and the systematics and stratigraphy of Wealden armoured dinosaurs. Geological Magazine, 130, 767-781.

Pereda-Suberbiola, J. 1994. Polacanthus (Ornithischia, Ankylosauria), a transatlantic armoured dinosaur from the Early Cretaceous of Europe and North America. Palaeontographica Abteilung A 232(4-6):133-159.

Pereda-Suberbiola, J. & Barrett. P.M., 1999. A systematic review of ankylosaurian dinosaur remains from the Albian-Cenomanian of England, Special Papers in Palaeontology, 60: 177-208.

2011 in Paleontology

2011-12-31T08:52:00.000-08:00

Fig 1.- A selection of species described in 2011.

It’s time for a retrospective of year 2011 in the paleontological field. Besides the description and discovery of new species, here is my pick of the top stories that marked the year:

150th anniversary of the description of Archaeopteryx

2011 is a fitting anniversary year for Archaeopteryx with the unveiling of the 11th specimen, the ICZN decision to make the London skeleton the new type for the genus (originally based on a single feather). The systematic position of the transitional fossil is still uncertain with two papers challenging its place at the base of the avialian tree while another puts it back on. An attempt has also been made to reconstruct the color of the London holotype feather.

Fig. 2.- Archaeopteryx.

References:
R. Carney, J. Vinther, M. Shawkey, L. d’Alba & J. Ackermann. 2011. Black Feather Color in Archaeopteryx. 2011 Society of Vertebrate Paleontology Annual Meeting Abstracts, p 84.

Michael S. Y. Lee & Trevor H. Worthy. 2011. Likelihood reinstates Archaeopteryx as a primitve bird. Biology letters. Published online before print.

Darren Naish, Gareth Dyke, Andrea Cau, François Escuillié and Pascal Godefroit. 2011. A gigantic bird from the Upper Cretaceous of Central Asia. Biology Letters. Published online before print. Electronic supplementary info.

Xing Xu, Hailu You, Kai Du and Fenglu Han. 2011. An Archaeopteryx-like theropod from China and the origin of Avialae. Nature 475: 465–470.

ICZN. 2011. OPINION 2283 (Case 3390) Archaeopteryx lithographica von Meyer, 1861 (Aves): conservation of usage by designation of a neotype. Bulletin of Zoological Nomenclature 68 (3): 230–233.

Fig 3.- Polycotylus giving live birth.

Plesiosaur viviparity

The discovery of a fossil plesiosaur (Polycotylus) with a well-developed fetus in its womb strongly suggests that these marine reptiles were giving live birth.

Reference: O'Keefe, F.R.; and Chiappe, L.M. 2011. Viviparity and K-selected life history in a Mesozoic marine plesiosaur (Reptilia, Sauropterygia). Science 333 (6044): 870–873.

Fig 4.- Velociraptor captured with an IR camera.

Theropods were nocturnal

The analysis of scleral rings of many extinct taxa suggests that most theropods and some pterosaurs hunted at nights whereas the herbivorous dinosaurs were mostly diurnal.

Reference: Schmitz, L. and Motani R. 2011. Nocturnality in dinosaurs inferred from scleral ring and orbit morphology. Science 332, 705.

Fig 5.- Microraptor.

Microraptor ate birds

We already knew that the four-winged dromaeosaur Microraptor was eating small mammals but a new gut content study of one specimen of this dinosaur shows that it also fed on birds.

Reference: O’Connor, Zhou & Xu. 2011. Additional specimen of Microraptor provides unique evidence of dinosaurs preying on birds. PNAS.

Fig 6.- Deinonychus.

A new model for Deinonychus predatory behavior

Deinonychus might have use its powerful claws to pinned down its prey in a manner similar to modern day eagles.

References: Fowler, D. W.; Freedman, E. A.; Scannella, J. B.; Kambic, R. E. 2011. The Predatory Ecology of Deinonychus and the Origin of Flapping in Birds. PLoS ONE 6 (12): e28964.

Fig 7.- Eodromaeus.

Eodromaeus murphi, the earliest theropod?

This little critter might be the earliest and most primitive theropod to date, if indeed Eoraptor is reclassified as a basal sauropodomorph.

Reference: R. N. Martinez, P. C. Sereno, O. A. Alcober, C. E. Colombi, P. R. Renne, I. P. Montañez, and B. S. Currie. 2011. A basal dinosaur from the dawn of the dinosaur era in southwestern Pangaea. Science 331(6014):206-210.

Fig 8.- Camarasaurus herd.

Teeth gave proof of Camarasaurus seasonal migration

… and apparently they traveled quite a long distance in search of food. The technique of teeth analysis for isotopic content shows lots of promise for understanding behavior of creatures long gone.

Reference: H. C. Fricke, J.Hencecroth, M.E. Hoerner. 2011. Lowland–upland migration of sauropod dinosaurs during the Late Jurassic epoch. Nature. Advanced online publication.

Fig 9.- Diania.

Diania, the “walking cactus”

The Lower Cambrian Diania cactiformis is the first fossil of lobopod with jointed legs, and therefore a possible missing link to the Arthropods.

Reference: Jianni Liu, Michael Steiner, Jason A. Dunlop, Helmut Keupp, Degan Shu, Qiang Ou, Jian Han, Zhifei Zhang & Xingliang Zhang. 2011. An armoured Cambrian lobopodian from China with arthropod-like appendages. Nature. 470, 526–530.

Fig 10.- Juramaia.

Juramaia sinensis, the first eutherian

Juramaia from the Middle Jurassic of Liaoning, China, dislodged Eomaia from the Early Cretaceous as the first known placental mammal.

Reference: Z.-X. Luo, C.-X. Yuan, Q.-J. Meng and Q. Ji. 2011. A Jurassic eutherian mammal and divergence of marsupials and placentals. Nature 476:442-445.

Fig 11.- Shastasaurus.

Shastasaurus may have been a suction feeder

The giant ichthyosaurs of the Late Triassic might indeed have been specialized feeder that preyed on squids.

Reference: Sander PM, Chen X, Cheng L, Wang X (2011) Short-Snouted Toothless Ichthyosaur from China Suggests Late Triassic Diversification of Suction Feeding Ichthyosaurs. PLoS ONE 6(5): e19480.

Fig 12.- Cryptolacerta.

Cryptolacerta hassiaca, the most primitive worm lizard

The modern amphisbaenians are burrowing limbless creatures that superficially resemble earthworms, but Cryptolacerta confirm their link to lizards.

Reference: Müller J., Hipsley C.A., Head J.J., Kardjilov N., Hilger A., Wuttke M. & reisz R.R. 2011. Eocene lizard from Germany reveals amphisbaenian origins. Nature 473, 364-367.

Fig 13.- The Triassic Kraken.

The Artsy Kraken

And finally, 2011 was marked by one outrageous claim about giant cephalopods playing with giant ichthyosaur bones.

Happy New Year 2012, Folks!

Original artworks on Paleoexhibit are copyrighted to Nobu Tamura. Do not use without permission (Email: nobu dot tamura at yahoo dot com)

Kronosaurus queenslandicus

2011-12-23T15:05:00.000-08:00

Fig. 1.- Reconstruction of Kronosaurus queenslandicus chasing a plesiosaur.

The most famous of the pliosaurs before WWD eclipsed it with an oversized Liopleurodon. This large (9-10 meters) marine reptile lived in the open oceans of Australia during the Aptian-Albian stage of the Early Cretaceous and was hunting large preys such as the long-necked plesiosaurs. It is known from at least three individuals, one being the iconic Harvard skeleton which was reconstructed with too many dorsal vertebrae making Kronosaurus a bit longer than it really was. A second species, named Kronosaurus boyacensis was found in Northern Colombia.

Original artworks on Paleoexhibit are copyrighted to Nobu Tamura. Do not use without permission (Email: nobu dot tamura at yahoo dot com)

References:

Hampe O. 1992. Ein großwüchsiger Pliosauride (Reptilia: Plesiosauria) aus der Unterkreide (oberes Aptium) von Kolumbien. Courier Forschungsinstitut Senckenberg 145: 1-32.

Longman H. A. 1924. A new gigantic marine reptile from the Queensland Cretaceous, Kronosaurus queenslandicus new genus and species. Memoirs of the Queensland Museum 8: 26–28.

Aegyptocetus tarfa

2011-12-21T08:49:00.000-08:00

The fossil of this early primitive whale was found cut into multiple slabs from a marbleized limestone imported in Italy. Put back together, it reveals an unusual Protocetid whale with a peculiar skull angled more like the Remingtonocetids such as Remingtonocetus and Dalanistes than the other protocetids and the basilosaurids. Bite marks on the ribs indicated that this particular individual was attacked by a large shark. The fossil came from the Gebel Hof Formation (Middle Eocene) of Wadi Tarfa in the Eastern Desert of Egypt.

Original artworks on Paleoexhibit are copyrighted to Nobu Tamura. Do not use without permission (Email: nobu dot tamura at yahoo dot com)

Reference:

G. Bianucci and P. D. Gingerich. 2011. Aegyptocetus tarfa, n. gen. et sp. (Mammalia, Cetacea), from the middle Eocene of Egypt: clinorhynchy, olfaction, and hearing in a protocetid whale. Journal of Vertebrate Paleontology 31(6):1173-1188

Spinops sternbergorum

2011-12-09T22:11:00.001-08:00

Fig 1.- Life reconstruction of Spinops sternbergorum.

This dinosaur was “rediscovered” within the precinct of the Natural History Museum in London, almost a century after it was excavated in the Dinosaur Park Formation in Alberta, Canada. It was only very recently realized that the long forgotten skull fragments belong to a new species.

Original artworks on Paleoexhibit are copyrighted to Nobu Tamura. Do not use without permission (Email: nobu dot tamura at yahoo dot com)

Fig 2.- Detail.

Reference:

Farke, A.A., Ryan, M.J., Barrett, P.M., Tanke, D.H., Braman, D.R., Loewen, M.A., and Graham, M.R. 2011. A new centrosaurine from the Late Cretaceous of Alberta, Canada, and the evolution of parietal ornamentation in horned dinosaurs. Acta Palaeontologica Polonica 56 (4): 691–702.

Abstract: In 1916, a centrosaurine dinosaur bonebed was excavated within the Campanian−aged deposits of what is now Dinosaur Provincial Park, Alberta, Canada. Specimens from this now−lost quarry, including two parietals, a squamosal, a skull missing the frill, and an incomplete dentary, were purchased by The Natural History Museum, London. The material was recently reprepared and identified herein as a previously unknown taxon, Spinops sternbergorum gen. et sp. nov. Based upon the available locality data and paleopalynology, the quarry lies in either the upper part of the Oldman Formation or the lower part of the Dinosaur Park Formation. The facial region of the partial skull is similar to putative mature specimens of Centrosaurus spp. and Styracosaurus albertensis, with short, rounded postorbital horncores and a large, erect nasal horncore. Parietal ornamentation is consistent on both known parietals and is unique among ceratopsids. Bilateral, procurved parietal hooks occupy the P1 (medial−most) position on the dorsal surface of the parietal and are very similar to those seen in Centrosaurus apertus. Epiparietals in the P2 or possibly P3 position (lateral to P1) manifest as extremely elongate, caudally directed spikes, unlike the condition in C. apertus, S. albertensis, or any other “derived” centrosaurine. Cladistic analysis suggests that S. sternbergorum is closely related to Centrosaurus and Styracosaurus. Historically, based upon the condition in Styracosaurus and related centrosaurines, it was assumed that the medial−most elongated spikes on centrosaurine parietals correspond to the P3 epiparietal position. The exception illustrated in the new taxon suggests that homologies of epiparietals among basal centrosaurines (e.g., Albertaceratops and Diabloceratops) and derived centrosaurines (e.g., Styracosaurus and “pachyrhinosaurs”) should be reconsidered. The medially−placed, caudally−directed “P3” process of basal centrosaurines may, in fact, be homologous with P2.

Cuspicephalus scarfi

2011-12-04T17:06:00.001-08:00

Fig 1.- Reconstruction of Cuspicephalus scarfi.

In the series of British prehistoric animals, let me this time introduce you to a pterosaur. Cuspicephalus is known from a partial skull unearthed in the Kimmeridge Clay Formation (Late Jurassic) of Dorset. This critter is possibly related to the Chinese Darwinopterus.

A new monofenestratan pterosaur from the Kimmeridge Clay Formation (Upper Jurassic, Kimmeridgian) of Dorset, England, David M. Martill and Steve Etches, Acta Palaeontologica Polonica (2011) in press

Abstract: A new specimen of slender skulled monofenestratan pterosaur from the Late Jurassic Kimmeridge Clay Formation of Dorset, UK, is referred to the new genus and species Cuspicephalus scarfi. The dentition and posterior skull morphology suggest affinities with Darwinopterus, but a close relationship cannot be proved. There are also some similarities with the pterodactyloid Germanodactylus cristatus, but the presence of teeth on the distal rostrum excludes it from that genus. Pterosaur remains are rare in the Upper Jurassic of the UK and this specimen represents the first significant cranial remains of a pterosaur from the Kimmeridge Clay Formation, and possibly the first non-pterodactyloid monofenestratan outside China.

Original artworks on Paleoexhibit are copyrighted to Nobu Tamura. Do not use without permission (Email: nobu dot tamura at yahoo dot com)

References:

David M. Martill and Steve Etches. 2011. A new monofenestratan pterosaur from the Kimmeridge Clay Formation (Upper Jurassic, Kimmeridgian) of Dorset, England. Acta Palaeontologica Polonica in press.

Thescelosaurus assiniboiensis

2011-12-04T16:37:00.001-08:00

Fig 1.- Reconstruction of Thescelosaurus.

Thescelosaurus is one of those dinosaurs, which did not gain much popularity despite the fact that it is today quite well known scientifically. Even the first specimen, excavated in 1891, remained in its shipping crates for years before being briefly described in 1913 receiving the appropriate name of ‘Thescelosaurus neglectus’ (meaning ‘neglected wondrous lizard’). Several skeletons, some quite complete, of this little ornithopod have been discovered since then in the United States and Canada. The genus received some media attention in year 2000, when one of the specimens from South Dakota named “Willo” was thought to contain a fossilized heart, a claim, which was later, rejected. To the currently recognized two species, T. neglectus and T. garbanii, a third, the smaller T. assiniboiensis, has just been described out of a specimen from Saskatchewan.

Brown; Caleb M.; Boyd, Clint A.; and Russell, Anthony P. 2011. A new basal ornithopod dinosaur (Frenchman Formation, Saskatchewan, Canada), and implications for late Maastrichtian ornithischian diversity in North America. Zoological Journal of the Linnean Society 163 (4): 1157–1198.

Abstract: A small, articulated basal ornithopod skeleton from the Frenchman Formation (late Maastrichtian) of Saskatchewan (RSM P 1225.1), previously referred to the taxon Thescelosaurus, differs from both recognized species of this taxon (Thescelosaurus neglectus and Thescelosaurus garbanii). The differences are taxonomically informative and we recognize this specimen as the holotype of a new species, Thescelosaurus assiniboiensis sp. nov., diagnosed by the presence of two autapomorphies, and displaying plesiomorphic traits more similar to those of Parksosaurus, than to those of the other Thescelosaurus species. The Frenchman Formation also harbours an intriguing faunal assemblage in which Thescelosaurus represents one of the most abundant dinosaur taxa, and preserves a relatively high proportion of small (putatively juvenile and subadult) specimens of many dinosaur taxa. Further work that increases the faunal sample from this formation, and that permits quantitative comparisons with contemporary formations, will determine whether or not these differences are well supported, and will determine their ultimate palaeobiological significance. Identification of a third species of Thescelosaurus from the late Maastrichtian of North America suggests that this taxon was more diverse than previously recognized, and shows an increase in diversity from the Campanian through the late Maastrichtian, contrasting the trends seen in most other ornithischian clades.

Original artworks on Paleoexhibit are copyrighted to Nobu Tamura. Do not use without permission (Email: nobu dot tamura at yahoo dot com)

References:
Brown; Caleb M.; Boyd, Clint A.; and Russell, Anthony P. 2011. A new basal ornithopod dinosaur (Frenchman Formation, Saskatchewan, Canada), and implications for late Maastrichtian ornithischian diversity in North America. Zoological Journal of the Linnean Society 163 (4): 1157–1198.

Aristosuchus pusillus

2011-12-04T12:54:00.001-08:00

Fig 1.- Reconstruction of Aristosuchus.

Continuing the series of British dinosaurs with the compsognathid Aristosuchus… This one is known from fragmentary postcranial remains from the Isle of Wight, dating from the Early Cretaceous Barremian stage, and originally described in 1876 by Sir Richard Owen (as “Poikilopleuron pusillus”). This little dinosaur was probably very similar to the Late Jurassic Compsognathus from Germany and France and measured about 2 meters in length.

Fig 2.- Reconstruction of Aristosuchus. Detail.

Original artworks on Paleoexhibit are copyrighted to Nobu Tamura. Do not use without permission (Email: nobu dot tamura at yahoo dot com)

References:

D. Naish. 2002. The historical taxonomy of the Lower Cretaceous theropods (Dinosauria) Calamospondylus and Aristosuchus from the Isle of Wight. Proceedings of the Geologists' Association 113:153-163.

R. Owen. 1876. Monograph on the fossil Reptilia of the Wealden and Purbeck formations. Supplement no. VII. Crocodilia (Poikilopleuron) and Dinosauria? (Chondrosteosaurus). [Wealden.]. The Palaeontographical Society, London 1876:1-7

H. G. Seeley. 1887. On Aristosuchus pusillus (Owen), being further notes on the fossils described by Sir R. Owen as Poikilopleuron pusillus, Owen. Quarterly Journal of the Geological Society of London 43:221-228

Jeholornis palmapenis

2011-11-30T00:03:00.001-08:00

Fig 1.- A reconstruction of Jeholornis palmapenis.

A new paper just came out (I am not quite sure if the pun in the abstract is intended):

New species of Jeholornis with complete caudal integument
Jingmai K. O'Connor, Chengkai Sun, Xing Xu, Xiaolin Wana & Zhonghe Zhou
Historical Biology, Available online: 29 Nov 2011

Abstract: The Early Cretaceous long bony-tailed bird Jeholornis prima displays characters both more basal than Archaeopteryx and more derived, exemplifying the mosaic distribution of advanced avian features that characterises early avian evolution and obfuscates attempts to understand early bird relationships. The current diversity of Jeholornithiformes is controversial, since multiple possibly synonymous genera were named simultaneously. Here, we provide the first definitive evidence of a second species belonging to this clade, and erect the new taxon J. palmapenis sp. nov. This new specimen reveals the tail integument of Jeholornithiformes, the morphology of which appears to have no aerodynamic benefit suggesting this clade evolved plumage patterns that were primarily for display.

Original artworks on Paleoexhibit are copyrighted to Nobu Tamura. Do not use without permission (Email: nobu dot tamura at yahoo dot com)

Archie the Black

2011-11-27T09:11:00.001-08:00

Fig. 1.- Archaeopteryx might have been robed in black.

There is definitely a lot going on for Archaeopteryx, on the 150th anniversary year of its first description by science. After the discovery of the 11th specimen, followed by its demotion then reinstatement as a basal bird, another piece of information has recently surfaced about the celebrated Urvogel: its color.

In a presentation this month at the 71st annual meeting of the Society of Vertebrate Paleontology in Las Vegas, Nevada, Ryan Carney and co-workers provided a glimpse of what Archaeopteryx may have look like in real life.

Using scanning electron microscopy and energy dispersive x-ray analyses, the team examined the iconic single feather attributed to Archaeopteryx, and detected fossilized melanosomes in it. By comparing the shape of the ancient pigment with those from 115 feathers coming from 87 species of modern birds, the team was able to determine that the color of the feather was black with 95% probability.

Fig 2.- The single feather examined for the color study of Archaeopteryx. The fossil has been described by von Meyer in 1861. (Picture credit: H. Raab, though Wikipedia)

Of course, the results from a single feather do not indicate that Archie was all robed in black like a raven, but they indicate that a least part of its plumage was dark.

Original artworks on Paleoexhibit are copyrighted to Nobu Tamura. Do not use without permission (Email: nobu dot tamura at yahoo dot com).

References:

R. Carney, J. Vinther, M. Shawkey, L. d’Alba & J. Ackermann. 2011. Black Feather Color in Archaeopteryx. 2011 Society of Vertebrate Paleontology Annual Meeting Abstracts, p 84.

Archaeopteryx is back on the Avialian tree...

2011-11-05T13:27:00.000-07:00

Fig 1.- Archaeopteryx back on its perch?

In the midst of the discovery of the 11th specimen of Archaeopteryx, almost complete (missing the head) with extensive feather impressions, a new paper published in Biology Letters, challenged the recent view expressed a few months earlier that it was not an Avialan (bird in the restricted sense) after all. Australian scientists Michael S. Y. Lee and Trevor H. Worthy, using the same sets of 374 characters than those defined by Xing Xu and co-workers in their Nature paper, employed a different and more sophisticated mathematical method in their phylogenetic analysis and arrived to a somewhat different conclusion.

Xu et al. used the maximum parsimony approach to obtain their evolutionary tree of birds and bird-like dinosaurs, while Lee used the more sophisticated maximum-likelihood and the related Bayesian inference methods. Under maximum parsimony, the preferred phylogenetic tree is the one that requires the least number of evolutionary changes to explain the observed sets of characters (or traits). Whereas generally valid, this assumption can be problematic in cases such as when some of the traits are evolving much faster than others or when some taxa have very long branches. The maximum-likelihood method is a seemingly more powerful (and computationally intensive) parametric statistical technique that uses an explicit model for character evolution and therefore is not subject to the same pitfalls. Maximum likelihood will pick the most probable tree that explains the observed data.

Fig 2.- Simplified tree according to Lee & Worthy, 2011.

The most important result of the Australian team new analysis of bird ancestry is that it puts solidly (in the sense that the measured level of accuracy given by the analysis is higher than with the parsimony approach) Archaeopteryx back on the Avialian tree as a basal bird. One of the consequences is that the typical forelimb-powered flight of birds would have only evolved once, while deinonychosaurian dinosaurs such as Microraptor would have discovered four-winged flight. Interestingly and on the side note, the odd scansopterygids, appear in the maximum likelihood analysis as deeply nested within the Avialians.

Is this new phylogenetic analysis establishing with certainty the evolutionary position of Archaeopteryx as the ancestral bird? Probably not… Pitfalls of the maximum parsimony method are reduced when taken more characters into account. We note for instance than in D. Naish & et al.’s study (2011), almost 3 times more characters (1025) were taken into account in a parsimony approach and the conclusion is somewhat similar to Xu et al. in the sense that Archaeopteryx is out of the Avialian tree.

References:

Michael S. Y. Lee & Trevor H. Worthy. 2011. Likelihood reinstates Archaeopteryx as a primitve bird. Biology letters. Published online before print.

Darren Naish, Gareth Dyke, Andrea Cau, François Escuillié and Pascal Godefroit. 2011. A gigantic bird from the Upper Cretaceous of Central Asia. Biology Letters. Published online before print. Electronic supplementary info.

Xing Xu, Hailu You, Kai Du and Fenglu Han. 2011. An Archaeopteryx-like theropod from China and the origin of Avialae. Nature 475: 465–470.

Teeth hold clues to dinosaur migrations

2011-10-29T08:20:00.000-07:00

Fig 1.- A migrating herd of Camarasaurus.

The teeth shape and wear pattern could already tell a lot about the diet of long gone creatures. New scientific methods applied to fossil teeth allow deciphering even more subtle behavioral habits. Last year, oxygen isotope analysis performed on Spinosaurus teeth has already shown that the popular back-sailed theropod dinosaur had a semiaquatic lifestyle. More recently, a detailed distribution analysis of ¹³C and ¹⁸O isotopes in the teeth of several sauropod dinosaurs was used to measure their body temperature. Now, in a new paper by Henry C. Fricke, Justin Hencecroth and Marie E. Hoerner published in the journal Nature, variations in the ¹⁸O isotope content measured in the teeth of the common Morrison formation sauropod Camarasaurus, lead strong support to the migratory behavior of those dinosaurs. The ratio of isotopes varies with the water the dinosaur drank and is recorded in the teeth enamel. Water from low elevation wetlands have higher ratio of ¹⁸O than those coming from surface water and precipitations at higher altitude. Comparisons of the teeth isotope ratio with those of ancient soils and their variations show that Camarasaurus was seasonally migrating for food, traveling as much as several hundreds of kilometers. During the wet months, they were staying in the lowland basin, but during the dry seasons when drought was quite possible, they moved uplands in search of vegetation. Pretty neat…

Original artworks on Paleoexhibit are copyrighted to Nobu Tamura. Do not use without permission (Email: nobu dot tamura at yahoo dot com)

References:

Amiot, R., Buffetaut, E., Lecuyer, C., Wang, X., Boudad, L., Ding, Z., Fourel, F., Hutt, S., Martineau, F., Medeiros, M., Mo, J., Simon, L., Suteethorn, V., Sweetman, S., Tong, H., Zhang, F., & Zhou, Z. (2010). Oxygen isotope evidence for semi-aquatic habits among spinosaurid theropods Geology, 38 (2), 139-142

Robert A. Eagle, Thomas Tütken, Taylor S. Martin, Aradhna K. Tripati, Henry C. Fricke, Melissa Connely, Richard L. Cifelli, and John M. Eiler, 2011, “Dinosaur Body Temperatures Determined from Isotopic (13C-18O) Ordering in Fossil Biominerals” Science. 333(6041):443-5.

H. C. Fricke, J.Hencecroth, M.E. Hoerner. 2011. Lowland–upland migration of sauropod dinosaurs during the Late Jurassic epoch. Nature. Advanced online publication.

A New Rebbachisaurid Sauropod from the Isle of Wight.

2011-10-26T08:46:00.000-07:00

Fig 1.- Reconstruction of Rebbachisaurus.

Rebbachisaurids are a rather obscure and poorly understood group of sauropod dinosaurs so far known only from the Early Cretaceous period of Africa, South America and Europe. A new find described in an article by Philip D. Mannion, Paul Upchurch and Stephen Hutt in this month issue of Cretaceous Research confirms the presence of this group on the Isle of Wight during the Early Cretaceous. The paper reports of a an anterior caudal vertebra from the Wessex Formation of Barremian age, discovered at Brightstone Bay on the Southwest coast of this little Island of the English Channel. No species name has been assigned to the fossil.

The type genus of the Rebbachisaurids, Rebbachisaurus was a sauropod, big plant-eating dinosaur similar to the famed Diplodocus, and member of the Diplodocoidea superfamily. It lived during the Early Cretaceous in what is now North Africa. It was first described in 1954 by R. Lavocat from fragmentary remains, consisting of a tail vertebra, a humerus (upper arm bone), a scapula (shoulder blade) and a sacrum, and collected from the Tegana Formation of Morocco. The species name is Rebbachisaurus garasbae. In 1960, A.F. de Lapparent described a second species, R. tamesnensis from various fragments of the Farak Formation of Niger, but this one is a bit dubious and can well belong to a completely different sauropod. More complete material from the Rio Limay Formation of Argentina including a partial skull has been referred to a third species, R. tessonei (Calvo & Salgado, 1995), and was used as proof of a land connection between Africa and South America in the Early Cretaceous, but the species has since been transferred to its own genus, Limaysaurus. So as today, the only species referable with certainty to the genus Rebbachisaurus is the Moroccan one described by Lavocat.

Fig 2.- Nigersaurus taqueti.

However, several closely related taxa have been described since then, mostly from South America, and a family, the Rebbachisauridae, has been erected by P. Sereno and co-workers in 1999 to regroup them. Although only known from Cretaceous strata, they appear to be basal members of the Diplodocoidea and therefore more primitive than the earlier Diplodocus and Apatosaurus from the late Jurassic period, indicating "a ghost lineage" from the Middle to Late Jurassic. Besides Rebbachisaurus and Limaysaurus, the Rebbachisaurids include the odd sauropod Nigersaurus taqueti, known from several well-preserved skeletons from the “Middle” (Aptian-Albian) Cretaceous of Niger, and described in the media as the “dinosaur with a vacuum cleaner mouth”. From the ten or so Rebbachisaurid taxa named so far, only Limaysaurus and Nigersaurus are known from relatively complete materials. All the others are very fragmentary so it is difficult to get a complete picture of this enigmatic family. One characteristic and common trait of this clade is the paddle-shaped scapular blade.

Besides Africa and South America, Rebbachisaurids were also living in Europe. The species Histriasaurus boscarottii, has been erected based on a few vertebrae from the Early Cretaceous (Hauterivian-Barremian) of Croatia (Dalla Vecchia, 1998), the most ancient member of the family so far and some materials from the Castrillo de la Reina Formation (Barremian-Aptian) of Spain have been reported by Pereda Superbiola et al. in 2003 and recently described in details under the name Demandasaurus darwini by Fernández-Baldor et al., in 2011. Finally, rebbachisaurids are also known from the Isle of Wight of England. A characteristic scapula (shoulder blade) collected by Nick Case in 1989 from the Wessex Formation on the southwest coast of the Isle of Wight has been described by Philip Mannion in 2009. In a recent cladistic analysis by Carballido et al., (2010), this British scapula comes, oddly, as a sister taxon of the South American Limaysausus tessonei. It is possible that the newly described caudal vertebra does belong to the same animal, even if the phylogenetic analysis placed it in a close kinship with the Spanish Demandasaurus and the African Nigersaurus, rather than with Limaysaurus. However, conclusions based on single incomplete bones are probably not to be entirely trusted until new discoveries are added to the analysis.

Original artworks on Paleoexhibit are copyrighted to Nobu Tamura. Do not use without permission (Email: nobu dot tamura at yahoo dot com)

References:

J. O. Calvo and L. Salgado. 1995. Rebbachisaurus tessonei sp. nov. a new Sauropoda from the Albian-Cenomanian of Argentina; new evidence on the origin of the Diplodocidae. GAIA 11:13-33.

J. L. Carballido, A. C. Garrido, J. L. Canudo and L. Salgado. 2010. Redescription of Rayososaurus agrioensis Bonaparte (Sauropoda, Diplodocoidea), a rebbachisaurid from the early Late Cretaceous of Neuquén. Geobios 43:493-503.

F. M. Dalla Vecchia. 1998. Remains of Sauropoda (Reptilia, Saurischia) in the Lower Cretaceous (Upper Hauterivian/Lower Barremian) limestones of SW Istria (Croatia). Geologica Croatica 51(2):105-134.

F. Torcida Fernández-Baldor, J. I. Canudo, P. Huerta, D. Montero, X. Pereda Suberbiola and L. Salgado. 2011. Demandasaurus darwini, a new rebbachisaurid sauropod from the Early Cretaceous of the Iberian Peninsula. Acta Palaeontologica Polonica 56(3):535-552

A. F. d. Lapparent. 1960. Les Dinosauriens du "Continental intercalaire" du Saharal central [The dinosaurs of the "Continental Intercalaire" of the central Sahara]. Mémoires de la Société géologique de France, nouvelle série 39(88A):1-57

R. Lavocat. 1954. Sur les dinosauriens du Continental Intercalaire des Kem-Kem de la Daoura [On the dinosaurs from the Continental Intercalaire of the Kem Kem of the Doura]. Comptes Rendus 19th Intenational Geological Congress, 1952 1:65-68.

P. D. Mannion. 2009. A rebbachisaurid sauropod from the Lower Cretaceous of the Isle of Wight, England. Cretaceous Research 30:521-526.

P. D. Mannion, P. Upchurch, and S. Hutt. 2011. New rebbachisaurid (Dinosauria: Sauropoda) material from the Wessex Formation (Barremian, Early Cretaceous), Isle of Wight, United Kingdom. Cretaceous Research 32:774-780

X. Pereda Suberbiola, F. Torcida, L. A. Izquierdo, P. Huerta, D. Montero and G. Pérez. 2003. First rebbachisaurid dinosaur (Sauropoda, Diplodocoidea) from the early Cretaceous of Spain: palaeobiogeographical implications. Bulletin de la Societé Géologique de France 2003(5):471-479

L. Salgado, A. Garrido, S. E. Cocca and J. R. Cocca. 2004. Lower Cretaceous rebbachisaurid sauropods from Cerro Aguada del León (Lohan Cura Formation), Neuquén province, northwestern Patagonia, Argentina. Journal of Vertebrate Paleontology 24(4):903-912.

P. C. Sereno, A. L. Beck, D. B. Dutheil, H. C. E. Larsson, G. H. Lyon, B. Moussa, R. W. Sadleir, C. A. Sidor, D. J. Varricchio, G. P. Wilson, and J. A. Wilson. 1999. Cretaceous sauropods from the Sahara and the uneven rate of skeletal evolution among dinosaurs. Science 286:1342-1347.

Scelidosaurus harrisoni, a basal thyreophoran from southern England

2011-10-22T10:18:00.000-07:00

Fig 1.- A reconstruction of Scelidosaurus harrisonii.

The Black Ven cliff between Charmouth and Lyme Regis, in Dorset, southern England is world famous for its Early Jurassic fossils of marine animals such as ammonites and ichthyosaurs. It is also known for a single species of dinosaur that has only been found there, Scelidosaurus harrisoni. How this fully terrestrial animal ended up preserved in marine deposits is somewhat a mystery (carcasses were presumably washed to sea after death and quickly buried by layers of sand) but it allows getting a rare glimpse of the fauna that lived during the Early Jurassic period on the islands of Europe (Most of Western Europe was under a shallow sea at that time).

Scelidosaurus was known from quite some time having been described in 1861 by Sir Richard Owen based on a skull and various non-associated postcranial bits discovered near the village of Charmouth. The original material contains a right knee joint, a femur fragment and a phalanx (finger bone) that proved later to belong to one or several type of megalosaurs (theropod dinosaurs) (Newman, 1968). Some other elements described by Owen as belonging to a juvenile Scelidosaurus proved later to be from a hypsilophodont. In the meantime, the postcranial skeleton associated to the original skull was uncovered and described by Owen in 1862. He named the species Scelidosaurus harrisonii, in honor of its discoverer, James Harrison.

Fig 2.- Original skull of Scelidosaurus in Owen's 1861 description of the genus. This skull is presently the lectotype as the holotype (a femur fragment) turned out to belong to a megalosaur.

These were the only fossils of the animal known for over a century and the exact affinities of the new dinosaur remained uncertain until fairly recently. The characteristic dermal scutes that make a kind of armor covering the body pointed to a close relationship with others armored ornithischians such as the stegosaurs, the ankylosaurs or the fabrosaurs. It was in turn considered a primitive stegosaur (von Zittel, 1902, Romer, 1956), an ankylosaur (Romer, 1968), a basal ornithopod (Thurlborn, 1977) and then generally considered a primitive ornithischian of some sort. A second skull previously described as a juvenile Scelidosaurus (Rixon, 1968) might actually belong to a hypsilophodont. Scutes from the Kayenta formation in Arizona were attributed to Scelidosaurus, which would indicate a large geographical range for the genus (Padian, 1989), but this identification has been questioned.

The uncertainty has dwindled in the last decade or so thanks in part to the fact that the original specimen described by Owen has been acid prepared so that it can be studied more thoroughly (Norman, 1996). Also, new specimens of Scelidosaurus began to turn up in the 1990s. Dave Martill described two of them in 1991 and 2000. The first is a rather complete articulated skeleton including skull fragments. It was found in 1985 near Charmouth in the Black Ven marls of Upper Sinemurian age. The second consists of a set of 8 articulated tail vertebrae and was acquired in 1998 from a private collection at the death of his owner, Prof. John Challinor. It unfortunately misses information about its provenance. A palynological analysis however indicates an Early Jurassic age from the same period as the Owen specimen (Late Hettangian- Sinemurian). Interestingly, both specimens show kerogenized traces of soft tissues indicating that the scutes (osteoderms) were covered by a horny sheath. A third specimen was collected in the same area between Charmouth and Lyme Regis in 2000 by a local fossil collector, David Sole. It has been described as the most complete skeleton of a dinosaur ever found in the UK.

Carpenter (2001) places Scelidosaurus as a basal ankylosaur. However, most of the recent phylogenetical analysis including the latest comprehensive one on the Ankylosauria (Thompson et al., 2011) points toward an ancestral position of Scelidosaurus relatively to both the stegosaurs and ankylosaurs, as a basal member of the thyreophorans. Other genera probably related to it include the gracile Scutellosaurus lawleri from the Kayenta formation in Arizona (Sinemurian-Plienbaschian), and the rather enigmatic Emausaurus ernsti from the Toarcian of Germany. Tatisaurus oeheleri from the Lufeng formation of Yunnan might be another relative, although the remains are so fragmentary that it is difficult to be sure. The same can be said of Bienosaurus lufengensis from the same formation known from fragments of a skull, and Lusitanosaurus liasicus from the Early Jurassic of Portugal, also known from a few skull fragments and teeth.

Fig 3.- Cast of a nearly complete skeleton of Scelidosaurus harrisonii found in 2000 and on display at the Charmouth Heritage Coast Center (photo by User:Ballista via wikipedia, CC3.0 licensed).

Scelidosaurus was a 4-meter long herbivorous dinosaur that probably walked on all fours although it was possibly able to stand on its hind legs from time to time. The body was covered with bony scutes called osteoderms as a protection against predators. Contrary to earlier depictions of the animal as a bulky quadruped, Scelidosaurus was probably more gracile in appearance with a relatively long neck compared to stegosaurs and ankylosaurs.

Original artworks on Paleoexhibit are copyrighted to Nobu Tamura. Do not use without permission (Email: nobu dot tamura at yahoo dot com)

References:

K. Carpenter. 2001. Phylogenetic analysis of the Ankylosauria. In K. Carpenter (ed.), The Armored Dinosaurs. Indiana University Press, Bloomington 455-483a

D.M. Martill, 1991. Organically preserved dinosaur skin: taphonomic and biological implications. Modern Geology, 16, 61±68.

B. H. Newman. 1968. The Jurassic dinosaur Scelidosaurus harrisoni, Owen. Palaeontology 11(1):40-43

R. Owen. 1861. A monograph of a fossil dinosaur (Scelidosaurus harrisonii, Owen) of the Lower Lias, part I. Monographs on the British fossil Reptilia from the Oolitic Formations 1:1-14

R. Owen. 1862. A monograph of a fossil dinosaur (Scelidosaurus harrisonii, Owen) of the Lower Lias, part II. Monographs on the British fossil Reptilia from the Oolitic Formations 2:1-26.

K. Padian, 1989. Presence of the dinosaur Scelidosaurus indicates Jurassic age for the Kayenta Formation (Glen Canyon Group, northern Arizona). Geology. May 1989, v. 17; no. 5; p. 438-441

A.E. Rixon, 1968. The development of the remains of a small Scelidosaurus from a Lias
nodule. Mus. J. 67:315-321.

A. S. Romer. 1956. Osteology of the Reptiles, University of Chicago Press 1-772

A.S. Romer. 1968. Notes and Comments on Vertebrate Paleontology. Chicago Univ. Press, Chicago, 304 p.

R. S. Thompson, J.C. Parish, S. C. R. Maidment & P. M. Barrett, 2011. Phylogeny of the ankylosaurian dinosaurs (Ornithischia: Thyreophora), Journal of Systematic Palaeontology, in press.

R. A. Thulborn. 1977. Relationships of the Lower Jurassic dinosaur Scelidosaurus harrisonii. Journal of Paleontology 51(4):725-739.

K. A. von Zittel, 1902. Text-book of Palaeontology, V. II. (Transl. C. R. Eastman). Macmillan, London and New York, 283 p.

Two extraordinary paleontology finds this week: one good, one bad...

2011-10-15T08:43:00.000-07:00

Fig 1.- Speed painting of the giant prehistoric kraken.

In the Triassic period, giant squids were roaming the oceans to pray on large ichthyosaurs the size of a school bus. Mark McMenamin, a professor of Geology at Mount Holyoke College, MA, presented this claim at the last Geological Society of America conference in Minneapolis (October 10, 2011). The proof lays in the curious arrangement of vertebral disks observed in the remains of the ichthyosaur Shonisaurus. According to McMenamin, this can only be the work of some giant artsy prehistoric cephalopods portraying themselves on the sand with the bones of their hapless victims! This is probably the most ludicrous paleontological claim made since the treeosaur. Amazingly, some major news outlets took the bait (see for instance here).

Fig 2.- Reconstruction of the Kelheim theropod.

The second extraordinary announcement of the week is the discovery of a 98% complete articulated skeleton of a young theropod dinosaur in Germany, the most complete ever found in Europe. The discovery has been unveiled by Oliver Rauhut, conservator of the Bavarian Paleontological and Geological collections in Munich. The press release unfortunately gave very little details about it. The fossil has been uncovered near Kelheim in Bavaria, and is, I would guess in view of the geology of the region, of Late Jurassic age (and not 135 MYA i.e. Early Cretaceous as said in the news). Judging from the photo of the skeleton that came with the release, it looks to be a compsognathid with a very long tail. General proportions of the skull and limbs are strikingly similar to Juravenator. But what do I know about this amazing yet unnamed theropod? Let’s wait for the full description of the fossil that will hopefully be published in the upcoming months.

Original artworks on Paleoexhibit are copyrighted to Nobu Tamura. Do not use without permission (Email: nobu dot tamura at yahoo dot com)

Talos sampsoni, a new troodontid from Utah

2011-09-19T21:45:00.000-07:00

After the Chinese Linhevenator, yet, another troodontid, Talos sampsoni, has just been described in the current issue of PLoS ONE. This one is from the distinct and quite specific fauna of the Kaiparowits formation of Utah, which included the unique ceratopsians Kosmoceratops, Utahceratops and Nasutuceratops, the tyrannosaurid Teratophoneus, the hadrosaur Gryposaurus and the Oviraptosaur Hagryphus. Talos is essentially known from remains of the hindlimbs plus a few other bits such as some vertebrae, and a left ulna. It was probably similar in shape to the other derived troodonts with short forelimbs, long legs and had a sickle claw on each foot.

References:
Lindsay E. Zanno, David J. Varricchio, Patrick M. O'Connor, Alan L. Titus and Michael J. Knell. 2011. A new troodontid theropod, Talos sampsoni gen. et sp. nov., from the Upper Cretaceous Western Interior Basin of North America. PLoS ONE 9 (6): e24487.

Pachyrhinosaurus perotorum, new boreal dinosaur from Alaska

2011-09-18T10:13:00.000-07:00

Fig 1.- Pachyrhinosaurus perotorum.

Anthony R. Fiorillo, and Ronald S. Tykoski, from the Museum of Nature and Science, Dallas, TX, have just described a new species of Ceratopsian (Horned dinosaur), Pachyrhinosaurus perotorum from the Prince Creek formation of the North Slope in the northernmost region of Alaska. The species is based on two fragments of parietals (which in Ceratopsians are the bones that formed the frill) and a partial skull.

What makes P. perotorum special is that it was a boreal dinosaur. During the Late Cretaceous, Alaska was situated at latitudes similar or higher than its current geographical position, meaning that its northern inhabitants experienced, as of today, a yearly 6 month long winter night with freezing temperature. Polar dinosaurs are also known from the southern hemisphere with representatives of the early Cretaceous period such as the hypsilophodont Leallynasaura amicagraphica from Australia featured in WWD. The Late Cretaceous Prince Creek formation of Alaska, however, appears to be the richest trove of polar dinosaur bones from either hemisphere. The Kikak-Tegoseak Quarry where the P. perotorum remains were unearthed, also include bones of the raptors Dromaeosaurus albertensis and Troodon formosus as well as remains attributed to the tyrannosaur Gorgosaurus libratus, some hadrosaurs and the Pachycephalosaur Alaskacephale gangloffi.

Fig 2.- Pachyrhinosaurus canadensis.

P. perotorum is the third named species of the genus Pachyrhinosaurus which contains Ceratopsians with massive flattened bosses in place of the usual horns on the nose and above the eyes. The larger 6 meter long P. canadensis was described in 1950. It is known from the St Mary River (Upper Campanian-Lower Maastrichtian) and Horseshoe Canyon Formations (Lower Maastrichtian) of Alberta, Canada. The smaller 5 meter long P. lakustai, described in 2008 from the Wapiti Formation (Late Campanian) of Alberta, differs from P. canadensis by well-separated nasal and supraorbital bosses and by the presence of a comb of horns on the parietal bone just behind the eyes.

Fig 3.- Pachyrhinosaurus lakustai.

P. perotorum is the youngest (Lower Maastrichtian) of the three species, and about the same size as P. lakustai. It is characterized by the unique anterior parietal pair of horns just at the top edge of the parietal cavities (the large holes in the frill), and a narrow dome in a back portion of the nasal boss. The bizarre blunt rounded rostrum might just be an individual oddity (the partial skull is apparently from an aged individual). A recently discovered specimen numbered TMP 2002.76.1 (Housed at the Royal Tyrrel Museum), from the Dinosaur Park Formation, Alberta, which shows similarities with both Pachyrhinosaurus and Achelousaurus, might represent a fourth species.

Pachyrhinosaurus belongs to the Pachyrhinosauri tribe of the Centrosaurine Ceratopsian that also contains the basal genera with enlarged nasal horns Einiosaurus and Rubeosaurus, as well as the derived forms with nasal and supraorbital bosses, Achelousaurus.

Original artworks on Paleoexhibit are copyrighted to Nobu Tamura. Do not use without permission (Email: nobu dot tamura at yahoo dot com)

References:

P. J. Currie, W. Langston, and D. H. Tanke. 2008. A new species of Pachyrhinosaurus (Dinosauria, Ceratopsidae) from the Upper Cretaceous of Alberta, Canada. In P. J. Currie, W. Langston Jr., D. H. Tanke (eds.), in A New Horned Dinosaur from an Upper Cretaceous Bone Bed in Alberta. NRC Research Press, Ottawa 1-108.

A.R. Fiorillo, and R.S.T. Tykoski, R.S.T. 2011. A new species of the centrosaurine ceratopsid Pachyrhinosaurus from the North Slope (Prince Creek Formation: Maastrichtian) of Alaska. Acta Palaeontologica Polonica. In press.

Linhevenator tani, a new troodontid from China

2011-09-12T08:37:00.000-07:00

Fig 1.- Reconstruction of Linhevenator tani.

Troodontids are a family of very bird-like small theropods with long legs and enlarged braincases. Phylogenetically, they are placed alongside the dromaeosaurs (Velociraptor, Deinonychus and friends) among the Deinonychosaurians, a sister group to the birds. Fossils of troodonts were found in Asia, Europe and North America in sediments dating from the Upper Jurassic to the Upper Cretaceous periods. Some of the better known troodonts include the Early Cretaceous Mei long (the shortest name given to a dinosaur, and meaning “sleeping dragon” because its exceptionally preserved articulated skeleton has been found in a sleeping position) and the Late Cretaceous Troodon formosus from North America, which was originally described on the basis of a single characteristic serrated tooth, but which is now known from multiple fragmentary specimens (previously referred as "Stenonychosaurus").

Fig 2.- The holotype (LH V0021) of Linhevenator tani (Xu et al., 2011). Licensed under CC 2.5. Scale bar is 2 cm.

Xing Xu and colleagues are reporting in the September 2011 issue of the open access journal PLoS ONE, a new troodontid from the Late Cretaceous Wulansuhai Formation of Bayan Mandahu, Inner Mongolia. The Wulansuhai Formation is equivalent to the famous Mongolian dinosaur bearing Djadokhta Formation of Campanian age. This new species, Linhevenator tani is known from a partly articulated skeleton that includes the skull, several vertebrae, pelvic girdle and limb elements. Although badly weathered, the remains are of particular interest are they are to date the most complete ones from a Late Cretaceous Troodontid and therefore likely to shed new lights on the more derived members of this family. Linhevenator was a rather large species (around 2-3 meters in length) characterized by rather short arms (the humeri measured only 40% of the length of the femur) and with a sickle clawed second digit on each foot similar to those of the dromaeosaurs, although these may be in fact common traits to all derived troodontids such as Troodon and Saurornithoides.

References:
Xing Xu, Qingwei Tan, Corwin Sullivan, Fenglu Han and Dong Xiao. 2011. A Short-Armed Troodontid Dinosaur from the Upper Cretaceous of Inner Mongolia and its Implications for Troodontid Evolution. PLoS ONE 6 (9): e22916

Original artworks on Paleoexhibit are copyrighted to Nobu Tamura. Do not use without permission (Email: nobu dot tamura at yahoo dot com)