Ajancingenia yanshini

After more than 30 years, the oviraptorid "Ingenia" yanshini finally got a new name: officially, it is now Ajancingenia yanshini. This dinosaur, first described in 1981 by Rinchen Barsbold from a fragmentary skeleton, was originally christened "Ingenia" but this generic name turns out to be preoccupied by a nematode worm therefore necessitating a new denomination. The paper announcing the change of name was published in Zootaxa by one Jesse Easter and all sounded very well until I saw THIS!  Shame on you, Mr Easter, this is not cool... not cool at all.

Ref:

R. Barsbold. 1981. Bezzubyye khishchnyye dinozavry Mongolii [Toothless carnivorous dinosaurs of Mongolia]. Sovmestnaia Sovetsko-Mongol’skaia Paleontologicheskaia Ekspeditsiia Trudy 15:28-39

J. Easter. 2013. A new name for the oviraptorid dinosaur "Ingenia" yanshini (Barsbold, 1981; preoccupied by Gerlach, 1957).  Zootaxa. 3737(2), 184-190.

M. Mortimer. Theropod Database information on "Ingenia" published! ... by someone else

A. Cau. Il preoccupante caso del preoccupato Ingenia [AGGIORNAMENTO]

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Deinocheirus the magnificent

A tentative recon of Deinocheirus while awaiting the official publication describing two new skeletons

Apparently, the mysterious Deinocheirus was more freaking awesome than you could ever have imagined... as recently revealed at SVP 2013! Here is the abstract:

New Specimens of Deinocheirus mirificus from the Late Cretaceous of Mongolia

Lee, Yuong-Nam; Barsbold, Rinchen; Currie, Philip; Kobayashi, Yoshitsugu &  Lee, Hang-Jae.

Abstract: The holotype of Deinocheirus mirificus was collected by the Polish-Mongolian Palaeontological Expedition at Altan Uul III in 1965. Because the holotype was known mainly on the basis of giant forelimbs with scapulocoracoids, Deinocheirus has remained one of the most mysterious dinosaurs. Two new specimens of Deinocheirus were discovered in the Nemegt Formation of Altan Uul IV in 2006 and Bugin Tsav in 2009 by members of the Korea-Mongolia International Dinosaur Expedition (KID). Except for the skull, middle dorsal and most of the distal caudal vertebrae, the right forelimb, left manus, and both pedes, the remaining parts of the skeleton (Mongolian Paleontological Center [MPC]-D 100/127) including a left forelimb clearly identifiable as Deinocheirus were collected. The humerus (993 mm in length) is longer than the 938 mm humerus of the holotype. The Altan Uul IV specimen (MPC-D 100/128) is a subadult Deinocheirus (approximately 72% of MPC-D 100/127), which consists of post-cervical vertebrae, ilia,ischia, and hind limbs. Both specimens provide important paleontological evidence for exact postcranial reconstruction of Deinocheirus mirificus. Cladistic analysis indicates that Deinocheirus is a basal member of Ornithomimosauria, but many new unique skeletal features appear to be quite different from other ornithomimosaurs. These include extreme pneumaticity of tall, anterodorsally oriented distal dorsal neural spines (7~8times taller than centrum height) with basal webbing, fused sacral neural spines forming a midline plate of bone that extends dorsally up to 170% of the height of the ilium, ventrally keeled sacral centra, a well-developed iliotibialis flange, a posterodorsally projecting posterior iliac blade with a concave dorsal margin, a steeply raised anteriordorsal margin of the ilium, an anteriorly inclined brevis shelf, vertically well-separatediliac blades above the sacrum, an completely enclosed pubic obturator foramen, triangular pubic boot in distal view, vertical ridges on anterior and posterior edges of medial surface of the femoral head, and a robust femur that is longer than tibiotarsus. These features suggest that Deinocheirus (unlike other ornithomimosaurs) was not a fast running animal, but a bulky animal with a heavily built pelvis and hind limbs. However,the dorsal ribs are tall and relatively straight, suggesting that the animal was narrow-bodied. A large number of gastroliths (>1100 ranging from 8 to 87 mm) were collected from the abdominal region of MPC-D 100/127, suggesting Deinocheirus was an herbivore.

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

New Multituberculate fossil shows keys to their success

Reconstruction of Rugosodon eurasiaticus.

Multituberculates are a highly successful group of early mammals and they were surprisingly long lived having evolved in the Jurassic, survived the KT extinction event before disappearing during the Oligocene period. They are in fact the most long-lasting group of mammals, having survived at least 130 million years, more than any other group of mammals either alive or extinct. A new mostly complete fossil discovered in China, Rugosodon eurasiaticus, greatly help clarify the origin of the group. It shows that some of the key characteristics of the multituberculates, such as highly flexible spine and mobile ankle joints, evolved very early, and were probable the reasons of their success.

Reference:

Ref: Yuan C.-X., Ji Q., Meng Q.-J., Tabrum A. R., Luo Z.-X. 2013. Earliest evolution of multituberculate mammals revealed by a new Jurassic fossil. Science 341 (6147): 779–783. 

Abstract: Multituberculates were successful herbivorous mammals and were more diverse and numerically abundant than any other mammal groups in Mesozoic ecosystems. The clade also developed diverse locomotor adaptations in the Cretaceous and Paleogene. We report a new fossil skeleton from the Late Jurassic of China that belongs to the basalmost multituberculate family. Dental features of this new Jurassic multituberculate show omnivorous adaptation, and its well-preserved skeleton sheds light on ancestral skeletal features of all multituberculates, especially the highly mobile joints of the ankle, crucial for later evolutionary success of multituberculates in the Cretaceous and Paleogene. 


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And then there were nine...

The top right species is now synonymous with the top left one.

Up to 15 species of Psittacosaurus have been described in the scientific litterature, but a few are dubious and others have been shown to be synonymous. With the latest 3D geometric morphometric study of the skulls of the three species of Psittacosaurids from the Lujiatun beds of the Yixian Formation of China, this number is now down to nine: Hongshanosaurus houi and Psittacosaurus major are now taxonomically dead...

Psittacosaurus lujiatunensis

Here is the paper and abstract:
Hedrick BP, Dodson P (2013) Lujiatun Psittacosaurids: Understanding Individual and Taphonomic Variation Using 3D Geometric Morphometrics. PLoS ONE 8(8): e69265.

Abstract:

Psittacosaurus is one of the most abundant and speciose genera in the Dinosauria, with fifteen named species. The genus is geographically and temporally widespread with large sample sizes of several of the nominal species allowing detailed analysis of intra- and interspecific variation. We present a reanalysis of three separate, coeval species within the Psittacosauridae; P. lujiatunensis, P. major, and Hongshanosaurus houi from the Lujiatun beds of the Yixian Formation, northeastern China, using three-dimensional geometric morphometrics on a sample set of thirty skulls in combination with a reevaluation of the proposed character states for each species. Using these complementary methods, we show that individual and taphonomic variation are the joint causes of a large range of variation among the skulls when they are plotted in a morphospace. Our results demonstrate that there is only one species of Psittacosaurus within the Lujiatun beds and that the three nominal species represent different taphomorphotypes of P. lujiatunensis. The wide range of geometric morphometric variation in a single species of Psittacosaurus implies that the range of variation found in other dinosaurian groups may also be related to taphonomic distortion rather than interspecific variation. As the morphospace is driven primarily by variation resulting from taphonomic distortion, this study demonstrates that the geometric morphometric approach can only be used with great caution to delineate interspecific variation in Psittacosaurus and likely other dinosaur groups without a complementary evaluation of character states. This study presents the first application of 3D geometric morphometrics to the dinosaurian morphospace and the first attempt to quantify taphonomic variation in dinosaur skulls.

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

The Late Permian Diapsids, Part I

The Late Permian Diapsids, Part I

In a previous post, I have covered the emergence of the diapsids during the Late Carboniferous and Early Permian. We don't really know what happened next as the diapsidian fossil record is unfortunately very sketchy between the Kungurian when we left Araeoscelis gracilis and the very end of the Late Permian period when diapsids reappear as fossils in reasonable number at a handful of locations on the planet.

 Fig. 1.- Reconstructed skull of Lanthanolania ivakhnenko (after Modesto et al., 2003).

Through the entire Middle Permian, the diapsids constitute what scientists call a 'ghost lineage': we merely know they were there because their existence is attested before and after that time but no fossil has been found dating from that period. Well, almost... there is one single partial skull discovered in the Mezen River basin in the Arkhangel'sk province of Russia which was named Lanthanolania ivakhnenko (Modesto et al, 2003). This was a small neodiapsid, probably no more than 30 cm long judging from the 3 cm small skull. The fossil is the only diapsid found among hundreds of other amniote specimens in the Mezen river basin and was naturally overlooked, originally labeled as yet another specimen of the synapsid Mesenosaurus (the generic name Lanthanolania means 'forgotten ripper').  Diapsids were obviously a rare thing at that time, living in the shadows of the larger and more successful synapsids, anapsids and enormous amphibians. The specimen dates from the Uppermost Kazanian or the lowermost Tatarian around 260 MYA which translates into anything between the ICS Wordian (~265 MYA) and the ICS Wuchiapingian (~257 MYA) stages. Although the discovery of Lanthanolania created a little sensation among the specialists in filling the gap, it did not say much on the evolution of the group partly due to the quite fragmentary nature of the finds. All we know is that between the Early Permian and the Late Permian, the Araeoscelids were gone forever and that the terrestrial Neodiapsids survived and somehow diversified. 

Fig 2.- Reconstruction of Youngina capensis.

In the Late Permian, a motley crew of forms collectively and formerly called "Eosuchians" (which means “early crocs”) was present. The Eosuchians do not constitute a natural group and their classification and phylogenetic relations are a bit hazy. At first it appeared that the Eosuchians should be divided into the ancestors of the lepidosaurians (lizards, snakes and such) and the ancestors of the archosaurs (crocs, dinosaurs, etc...) but current understanding is that the story is more complicated than this. The most recent cladogram (Reisz et al., 2011) shows  a seemingly paraphyletic "younginiformes" group as the most basal eosuchians, with both terrestrial and aquatic forms, then the aquatic form Claudiosaurus (once thought to be a basal Sauropterygian), followed by some members of a family of terrestrial forms called "paliguanids", and finally the gliding coelurosauravids. None of them left any descendants and disappeared in the Early Triassic. Accompanying these "Eosuchians" in the Late Permian were the first members of the Archosauromorphs: the semi-aquatic protorosaurids.

Fig 3.- Skull of Youngina capensis.

Let's first go over the so-called "younginiformes", starting with the terrestrial ones. Youngina capensis was a small lizard-like creature that was first described from a partial skull (Broom, 1914) found in the Dicynodon assemblage zone of South Africa and dating from the latest Permian period. Youngina lived alongside a rich fauna of synapsids, including dicynodonts, gorgonopsids and biarmosuchians and anapsid reptiles, in what was a semi-arid environment. Since its original description, several fossils of Youngina, mostly skulls, were found, receiving different names (Youngoides, Youngopsis, etc...) that are all now considered to be synonymous to Youngina. One peculiar characteristics of Youngina is its single row of osteoderms on its back. A remarkable discovery consists of a set of 5 juvenile, fully articulated and complete individuals, indicating that those critters most certainly lived in a den (Smith &Evans, 1996).

The next two taxa are only tentatively placed among the younginids. Galesphyrus capensis, also described by Broom in 1914 is from the base of the Cistecephalus assemblage zone of South Africa (thus older than Youngina) and is known from a partial postcranial skeleton. Heleosuchus griesbachi, originally described by Owen (1876) as a species of Saurosternon, is known from a single specimen consisting of the posterior part of the skull and a partial postcranial skeleton. The fossil was thought to be lost until relocated in the Natural History Museum in Vienna, Austria (Carrol, 1987). The specimen is from South Africa from an unknown horizon and would date either from the Late Permian or the Early Triassic. Without good skull material, getting the exact affinities of these two animals is very difficult.

Fig 4.- Reconstruction of Thadeosaurus colcanapi.

From the Lower Sakamena formation of southern Madagascar originates Thadeosaurus colcanapi (Carroll, 1981) which is based on two nearly complete skeletons missing the skull and the lower parts of the limbs. This one was originally thought to belong to the European genus Datheosaurus, which is now known to be synonymous with the pelycosaur Haptodus (thus a Synapsid … it seems many of these early diapsids were first mistaken with a synapsid). As an intended pun, the name Thadeosaurus is simply an anagram of the name Datheosaurus, the only deliberate anagram of an animal scientific name that I am aware of. Thadeosaurus is known from several specimens, including juveniles, many being at first confused with the Tanzanian Tangasaurus (Currie & Carrol, 1984). It was a small lizard like creature measuring perhaps about 60 cm in length and characterized by a very long tail. Although found in marine strata, Thadeosaurus has no obvious adaptation for swimming indicating it was most probably a coastal fully terrestrial animal. The interesting thing about the Lower Sakamena formation is that this aquatic deposit contains an unusually large proportion of diapsid reptiles as compared to any other upper Permian deposits in the world. This is quite anomalous and the exact age of the deposits can be questioned. The age is based on palynological (fossil pollen) evidence and correlation of the vertebrate fauna with South Africa. One index fauna is the procolophonid Barasaurus which is similar to the South African Owenetta. But the latter was later also found in Early Triassic strata.

Let us conclude this tour of the terrestrial younginiformes with Kenyasaurus mariakanensis from the Early Triassic Maji-Ya-Chumvi formation of Kenya (Harris & Carroll, 1977). It is known from a single specimen lacking the skull and most of the pectoral girdle and forelimb, making its affinities hard to establish. This one was recently kicked out of the younginiformes. Like Thadeosaurus, it was found in marine strata but does not appear to have any specialization for aquatic environment. Therefore, it was probably a terrestrial form which measured about 50 cm in length.

Note also that two animals of that time, Heleosaurus and Apsisaurus, once considered being younginiformes turn out to be Synapsids of the varanopid sort.

Next, the marine “younginiformes”…

References:

Carroll, R. (1981). Plesiosaur ancestors from the Upper Permian of Madagascar. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, 293(1066), 315-383.

Carroll, R. (1987). Heleosuchus: An enigmatic diapsid reptile from the Late Permian or Early Triassic of southern Africa. Canadian Journal of Earth Sciences, 24, 664-667.

Currie, P., & Carroll, R. (1984). Ontogenetic changes in the eosuchian reptile Thadeosaurus. Journal of Vertebrate Paleontology, 4(1), 68–84.

Harris, J., & Carroll, R. (1977). Kenyasaurus, a new eosuchian reptile from the Early Triassic of Kenya. Journal of Paleontology, 51(1), 139-149.

Modesto, S., & Reisz, R. (2003). An enigmatic new diapsid reptile from the Upper Permian of Eastern Europe. Journal of Vertebrate Paleontology, 22(4), 851-855.

Olson, E. (1936). Notes on the skull of Youngina capensis Broom. The Journal of Geology, 44(4), 523-533.

Reisz, R. R., Modesto, S. P.  and Scott, D. M. (2011). A new Early Permian reptile and its significance in early diapsid evolution. Proceedings of the Royal Society B 278, 3731-3737

Smith, R., & Evans, S. (1996). New material of Youngina: evidence of juvenile aggregation in Permian diapsid reptiles. Palaeontology, 39(2), 289-303.

2012 in Paleontology

It’s time for a retrospective of year 2012 in the paleontological field. Many species were described that year and apart from a few obvious ones, it was quite difficult to decide what should make up the top ten stories. After multiple hesitations, here is my pick (not in particular order of importance):

1.- The Kelheim theropod unveiled in 2011 received its official scientific name as Sciurumimus albersdoerferi. More surprisingly, it turns out to be a Megalosauroid, making it the theropod the most distantly related to birds to show direct evidence of feathers.

Reference: O. W. M. Rauhut, C. Foth, H. Tischlinger and M. A. Norell. 2012. Exceptionally preserved juvenile megalosauroid theropod dinosaur with filamentous integument from the Late Jurassic of Germany. Proceedings of the National Academy of Sciences 29:11746-11751.

2.- At 9 meter in length, Yutyrannus huali is the largest dinosaur showcasing direct evidence of feathers. Yutyrannus is also a tyrannosauroid, moving the at least partial feather coverage idea for Tyrannosaurus rex, from good probability to almost certainty.

Reference: X. Xu, K. Wang, K. Zhang, Q. Ma, L. Xing, C. Sullivan, D. Hu, S. Cheng, and S. Wang. 2012. A gigantic feathered dinosaur from the Lower Cretaceous of China. Nature 484:92-95

3.- Echinoderms (starfish, urchins, sea lilies, etc…) are unique among animals in having a body with a fivefold symmetry. We know from embryology that they must have evolved from bilateral ancestors. The fossil record finally confirmed this with the discovery of Ctenoimbricata spinosa, a sea floor spiny animal which proved to be an early echinoderm with bilateral symmetry.

Reference: S. Zamora, I. A. Rahman, and A. B. Smith. 2012. Plated Cambrian Bilaterians Reveal the Earliest Stages of Echinoderm Evolution. PLoS ONE 7(6):e38296:1-e38296:11.

4.- Microraptor, the four-winged dinosaur that already made the headlines last year when it was discovered to feed on birds, reveals its true colors: the study of fossil pigments indicates it had the plumage of a crow: metallic black.

Reference: Q. Li. 2012. Reconstruction of Microraptor and the Evolution of Iridescent Plumage. Science 335: 1215-1219.

5.- Evidence of feathers was also found in the North American ostrich-mimic dinosaur Ornithomimus edmontonicus. While the body was covered with downy feathers, the arms in the adults had wing feathers, suggesting that mating display was the initial purpose of those, not flight.

Reference: D. K. Zelenitsky, F. Therrien, G. M. Erickson, C. L. Debuhr, Y.  Kobayashi, D. A.  Eberth, F.  Hadfield,   2012. Feathered Non-Avian Dinosaurs from North America Provide Insight into Wing Origins. Science 338 (6106): 510.

6.-  Mosasaurs form a group of highly specialized predators from the Late Cretaceous period,  related to modern day monitor lizards and perfectly adapted for swimming. The fossil of Pannoniasaurus inexpectatus is the first evidence that these predominantly marine creatures have also conquered freshwater.

Reference: L. Makádi, M. W. Caldwell, and A. Osi. 2012. The first freshwater mosasauroid (Upper Cretaceous, Hungary) and a new clade of basal mosasauroids. PLoS ONE 7(12):e51781.

7.-  Nyasasaurus parringtoni known from very fragmentary remains might have been the earliest representative of the dinosaur clade.

Reference: S. J. Nesbitt, P. M. Barrett, S. Werning, C. A. Sidor, and A. J. Charig. 2013. The oldest dinosaur? A Middle Triassic dinosauriform from Tanzania. Biology Letters 9(1):1-5.

8.- A morphometric study of archosaur skulls indicate that birds have the skull of baby dinosaurs. Our avian friends may have therefore evolved from neotenic dinosaurs retaining their juvenile characteristics through adulthood.

Reference: Bhullar, B., Marugán-Lobón, J., Racimo, F., Bever, G., Rowe, T., Norell, M., & Abzhanov, A. 2012. Birds have paedomorphic dinosaur skulls. Nature, 487, 223-226.

9.- A new phylogenetic analysis of the enigmatic Miocene creature known as Necrolestes patagonensis indicates that it was a survivor of an ancient lineage of primitive mammals thought to have disappeared at the end of the Cretaceous: the Meridiolestids.

Reference: G. W. Rougier, J. R. Wible, R. M. D. Beck and S. Apesteguía. 2012. The Miocene mammal Necrolestes demonstrates the survival of a Mesozoic nontherian lineage into the late Cenozoic of South America. Proceedings of the National Academy of Sciences of the United States of America 109 (49): 20053–20058.

10.- The Cetotheriids are a family of baleen whales that appeared during the Late Oligocene and thought to be extinct since the Late Pliocene. Not anymore: a new phylogenetic analysis indicates that the living Pygmy Right Whale (Caperea marginata) is in fact a modern surviving representative of this family.

Reference: R. E. Fordyce and F. G. Marx. 2013. The pygmy right whale Caperea marginata: the last of the cetotheres. Proceedings of the Royal Society B: Biological Sciences 280 (1753): 20122645.

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