There is little consensus on the systematic position of the colossal theropod dinosaur
Chilantaisaurus tashuikouensis from the Cretaceous (Aptian–?Albian or Upper Cretaceous)Ulansuhai Formation of Inner Mongolia, which has been recovered as a derived member of both Allosauroidea and Spinosauroidea by numerical phylogenetic analyses. Redescription of the type material of C. tashuikouensis reveals an unusual combination of morphological features that render determination of its systematic position problematic. It possesses anatomical features that have been proposed as synapomorphies of Neotetanurae: a preacetabular fossa on the ilium, and a wedge-shaped crosssection of the shaft of the thi ... Read more »

Cope’s rule, the tendency towards evolutionary increases in body size, is a long-standing macroevolutionary generalization that has the potential to provide insights into directionality in evolution; however, both the definition and identification of Cope’s rule are controversial and problematic. A recent study [J. Evol. Biol. 21 (2008) 618] examined body size evolution in Mesozoic birds, and claimed to have identified evidence of Cope’s rule occurring as a
result of among-lineage species sorting. We here reassess the results of this study, and additionally carry out novel analyses testing for within-lineage patterns in body size evolution in Mesozoic birds. We demonstrate that the nonphy ... Read more »

The rise and diversification of the dinosaurs in the Late Triassic, from 230 to 200 million
years ago, is a classic example of an evolutionary radiation with supposed competitive
replacement. A comparison of evolutionary rates and morphological disparity of basal dinosaurs and their chief “competitors,” the crurotarsan archosaurs, shows that dinosaurs exhibited lower disparity and an indistinguishable rate of character evolution. The radiation of Triassic archosaurs as a whole is characterized by declining evolutionary rates and increasing disparity, suggesting a decoupling of character evolution from body plan variety. The results strongly suggest that historical contingency, rather t ... Read more »

This study reports on the three-dimensional spatial arrangement and movements of the skeleton of Anhanguera santanae (Pterodactyloidea: Ornithocheiridae), determined using exceptionally well-preserved uncrushed fossil material, and a rigid-body method for analysing the joints of extinct animals. The geometric results of this analysis suggest that the ornithocheirids were inherently unstable in pitch and yaw. As a result, pitch control would
probably have been brought about by direct adjustment of the angle of attack of the wing, by raising or lowering the trailing edge from the root using the legs if, as is indicated in soft-tissue specimens of a number of unrelated pterosaur species, the ... Read more »

The analysis of some morphological characteristics of protoceratopoid skeletons, the extent of mobility of the vertebral column, and the probable adaptive significance of these features suggest that Bagaceratops had a mostly aquatic mode of life, Protoceratops was semiaquatic, Udanoceratops was facultatively aquatic, and Leptoceratops was predominantly terrestrial. Protoceratopoids were quadrupeds, with the prevalence of hind limbs, probably using slow or rapid trotlike gait. An asymmetrical locomotion was most likely impossible. On dry land, Bagaceratops and Protoceratops moved slowly. Udanoceratops and Leptoceratops
approximately equally used rapid and slow locomotor modes, although the ... Read more »

An exceptionally preserved subadult specimen (JRF 115H) of a hadrosaurid, Brachylophosaurus canadensis, from the Judith River Formation near Malta, Montana, contains abundant plant fragments concentrated within the body cavity. We examined the taphonomy of the carcass and analyzed the gut-region material to test whether the organic remains represent fossilized gut contents. The dinosaur was buried in a fluvial channel setting, and the excellent articulation, integument impressions, and lack of scavenging indicate rapid burial. The organic material occupies a volume of at least 5750 cm3, and
comparable material is not found outside the carcass. The carcass contents include 63% clay, 16% ... Read more »

A new oviraptorosaur, Similicaudipteryx yixianensis gen. et sp. nov. is described from the Jiufotang Formation (120 Ma) of the Jehol Group in western Liaoning, China, which is referred to the Caudipteridae based on a dagger-like pygostyle and the shape of the ilium that are most similar to those of Caudipteryx. It differs from other oviraptorosaurids in that the ratio of pubis to ilium length is 1. 46 and the presence of two large and deep hypapophyses on dorsal vertebrae. The known caudipterids have previously been found only from the Jianshangou Member of the Yixian Formation (125 Ma) of the Sihetun area in Liaoning Province. S. yixianensis represents the first caudipterid dinosaur from th ... Read more »

Cretaceous polar dinosaur faunas were taxonomically diverse, which suggests varied strategies for coping with the climatic stress of high latitudes. Some polar dinosaurs, particularly larger taxa such as the duckbill Edmontosaurus Lambe, 1917, were biomechanically and energetically capable of migrating over long distances, up to 2600 km.
However, current evidence strongly suggests many polar dinosaurs (including sauropods, large and small theropods, and ankylosaurs of New Zealand) overwintered in preference to migration. Certain groups also appear more predisposed to overwintering based on their physical inability (related to biomechanics, natural history, or absolute size) to migrate, su ... Read more »

We describe a new titanosaurian braincase (MML-194), from the Upper Cretaceous (middle Campanian–lower Maastrichtian) of Río Negro Province, Argentina. Among titanosaurs, this specimen resembles Bonatitan reigi, more than any other member of the clade; the similarity is based on the supraoccipital protuberance bearing a median groove (also present in Saltasaurus and Rapetosaurus), the prominent basal tubera, the exit for the nerve VII located on the prootic crest, the occipital condyle and the foramen magnum almost of the same width. This material allows to observe some internal structures that are not appreciable in other titanosaurs, such as the pituitary cavity, the dorsum sellae and the ... Read more »

A skin impression fossil of Gigantspinosaurus sichuanensis was found in the Upper Jurassic Shangshaximiao Formation in Zigong, Sichuan. The fossil, preserved on the dorsal face of the left shoulder, clearly shows scales of Gigantspinosaurus sichuanensis. These scales are generally arranged as a net, and most of them are pentagonal, a few being quadrilateral and hexagonal. The maximum inner radius of most scales range from 5.7 to 9.2 mm. The scales are connected with each other by grooves. Scattered within small scales are a few pentagonal or hexagonal large scales, with each large scale surrounded by 13—14 scales. The surface of the scales is rough with string—like ridges. The stringy ridge ... Read more »

Teeth from the Early Cretaceous Napai Formation of Fusui County, Guangxi Zhuang Autonomous Region (South China), initially described as the sauropterygian Sinopliosaurus fusuiensis, are redescribed as belonging to a spinosaurid theropod closely allied to Siamosaurus suteethorni, from the Early Cretaceous of Thailand. This identification extends to China the geographical range of Asian spinosaurs, previously reported from Thailand and Japan.

Most titanosaur dinosaurs are represented by incomplete skeletal elements lacking articulated pes. An exceptionally preserved specimen from the Late Campanian–Early Maastrichtian strata of Patagonia (Argentina) provides new data on pedal morphology and the evolutionary trends of these huge dinosaurs. This finding is one of the few articulated titanosaur pes known in the world, and shows a phalangeal formula of 2-2- ... Read more »

An incomplete braincase from the Upper Cretaceous Portezuelo Formation of northwestern Patagonia (Neuquén Province, Argentina) is described. The specimen preserves the lateral walls formed by the laterosphenoid, probably part of the orbitosphenoid, prootic, the exoccipital-opisthotic complex and fragments of the frontal, parietal and basisphenoid. Both inner ears are preserved allowing the production of latex endoc ... Read more »

The complete osteology of the basal sauropod Tazoudasaurus naimi from the late Early Jurassic Toundoute continental series of Ouarzazate Province, Morocco, is presented. The described material belongs to juvenile to adult individuals. The skeleton of Tazoudasaurus is virtually complete except for the skull and presents a combination of plesiomorphic and apomorphic sauropodomorph characters. Phylogenetic analysis in ... Read more »

An abelisaurid ungual phalanx of pedal digit III from the Late Cretaceous of NW Madagascar is here figured and described for the first time. Other materials include pedal phalanges whose figures and description increase the knowledge on the pes variability of the Malagasy Abelisauridae (e.g., ungual I and phalanx III-1 proportions and structures), support the identification of the pedal elements (e.g., phalanx III- ... Read more »

A new basal non-pterodactyloid pterosaur, Raeticodactylus filisurensis gen. et sp. nov., is reported. It has been discovered in shallow marine sediments from the Upper Triassic of the lowest Kössen beds (late Norian/early Rhaetian boundary) in the central Austroalpine of Canton Grisons (Switzerland). The disarticulated specimen is comprised of an almost complete skull and a partial postcranial skeleton. A high and ... Read more »

We report the discovery of basal abelisaurid and carcharodontosaurid theropods from the mid Cretaceous (Aptian–Albian, ca. 112 Ma) Elrhaz Formation of the Niger Republic. The abelisaurid, Kryptops palaios gen. et sp. nov., is represented by a single individual preserving the maxilla, pelvic girdle, vertebrae and ribs. Several features, including
a maxilla textured externally by impressed vascular grooves and a n ... Read more »

A new large theropod, Orkoraptor burkei nov. gen. et nov. sp., from the Upper Cretaceous (Maastrichtian) Pari Aike Formation of southern Patagonia is based on a postorbital, quadratojugal, coronoid?, several teeth, an atlantal intercentrum and neurapophysis, two caudal vertebrae, and the proximal half of tibia. This new theropod exhibits characteristics of maniraptorans (i.e., coelurosaurians more derived than tyra ... Read more »

Dinosauriform and dinosaurian remains are rare from the Late Triassic Dockum Group of
Texas. Using a synapomorphy-based approach, we evaluate new remains and previously reported remains assigned to Dinosauria from the Post Quarry (Garza County, Texas) and find that that the assemblage contains a non-dinosaur dinosauriform, an early saurischian, and a coelophysoid theropod. A partially associated skeleton of a di ... Read more »

The dinosaur fauna of the palynologically dated lower Berriasian Skyttegård Member of the Rabekke Formation on the Baltic island of Bornholm, Denmark, is represented by isolated tooth crowns. The assemblage is restricted to small maniraptoran theropods, assigned to the
Dromaeosauridae incertae sedis and Maniraptora incertae sedis. The dromaeosaurid teeth are characterized by their labiolingually compressed and d ... Read more »