Psittacosaurus is the most speciose nonavian dinosaur genus, represented by at least 10 (and possibly as many as 19) species uncovered over a wide geographic range. Here, we report a new species of large-bodied Psittacosaurus from the Ondai Sayr locality in central Mongolia, which has hitherto produced only one other Psittacosaurus specimen. This new species is char¬ acterized by: (1) an elongate snout, with a gently inclined rostronasal margin, (2) a cranium dorsally convex rather than flat, (3) a subtemporal length less than 40% of total skull length, (4) a maxillary lamina that cups the posterior toothrow, (5) five premaxillary foramina arrayed in an arc, (6) an antorbital fossa as long as it is wide, and (7) a palpebral with a well-developed posterior tonguelike process. Psittacosaurus amitabha is resolved as the most basal member of the genus Psittacosaurus in our phylogenetic analysis. This taxon expands our knowledge of the already-speciose genus Psittacosaurus as well as our understanding of the Ondai Sayr fauna, which is poorly known in comparison to other Mongolian Early Cretaceous localities.both of which are known from the Lujiatun beds of the Yixian Formation, were found to form one morphometric cluster using 3D geometric morphometries (Hedrick and Dodson, 2013), leading the authors to pronounce P. major a junior synonym of P. lujiatunensis.There are several problems with this analysis. The authors did not retrodeform the speci¬ mens, incorporated juveniles and adults in the same dataset, and did not reference the range of intraspecific variation present among modern animals. Therefore, we consider their argument for synonymizing these species inconclusive and continue to treat them as separate taxa in this study.Here we describe a new species of Psittacosaurus, based on a well-preserved skull found in association with fragmentary postcrania. This specimen is notable for: (1) its large size (only matched by Psittacosaurus major and Psittacosaurus sibiricus), (2) its nearly complete and undistorted braincase, and (3) being the first specimen of the genus Psittacosaurus recovered from the Ondai Sayr locality since AMNH FARB 6253 nearly 100 years ago. AMNH FARB AMNH FF AMNH FI CAGS-IG IGM LH

In 2001, a nearly complete sub-adult Tenontosaurus tilletti was collected from the Antlers Formation (Aptian-Albian) of southeastern Oklahoma. Beyond its exceptional preservation, computed tomography (CT) and physical examination revealed this specimen has five pathological elements with four of the pathologies a result of trauma. Left pedal phalanx I-1 and left dorsal rib 10 are both fractured with extensive callus formation in the later stages of healing. Left dorsal rib 7 (L7) and right dorsal rib 10 (R10) exhibit impacted fractures compressed 26 mm and 24 mm, respectively. The fracture morphologies in L7 and R10 indicate this animal suffered a strong compressive force coincident with the long axis of the ribs. All three rib pathologies and the pathological left phalanx I-1 are consistent with injuries sustained in a fall. However, it is clear from the healing exhibited by these fractures that this individual survived the fall. In addition to traumatic fractures, left dorsal rib 10 and possibly left phalanx I-1 have a morphology consistent with post-traumatic infection in the form of osteomyelitis. The CT scans of left metacarpal IV revealed the presence of an abscess within the medullary cavity consistent with a subacute form of hematogenous osteomyelitis termed a Brodie abscess. This is only the second reported Brodie abscess in non-avian dinosaurs and the first documented occurrence in herbivorous dinosaurs. The presence of a Brodie abscess, known only in mammalian pathological literature, suggest mammalian descriptors for bone infection may be applicable to non-avian dinosaurs.

Cenomanian mesoeucrocodylians from North

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