Terry A. Gates

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Prior studies of Mesozoic biodiversity document a diversity peak for dinosaur species in the Campanian stage of the Late Cretaceous, yet have failed to provide explicit causal mechanisms. We provide evidence that a marked increase in North American dinosaur biodiversity can be attributed to dynamic orogenic episodes within the Western Interior Basin (WIB).(More)
A new species of the hadrosaurine hadrosaurid Gryposaurus was discovered in the late Campanian Kaiparowits Formation of southern Utah. Gryposaurus monumentensis, sp. nov. is distinguished from other Gryposaurus species by possessing a more robust skull, enlarged clover-shaped prongs on the predentary oral margin, an anteroposteriorly narrow infratemporal(More)
A new hadrosaurid dinosaur, Acristavus gagslarsoni, is here named on the basis of several autapomorphic characteristics of the frontal, postorbital, and dentary. Acristavus is a member of the newly erected clade Brachylophosaurini, which along with its other members, Brachylophosaurus and Maiasaura, constitutes the earliest hadrosaurine hadrosaurid clade.(More)
Definitive therizinosaurid cranial materials are exceptionally rare, represented solely by an isolated braincase and tooth in the North American taxon Nothronychus mckinleyi, the remarkably complete skull of the Asian taxon Erlikosaurus andrewsi, and the lower hemimandibles of Segnosaurus galbinensis. To date, comprehensive descriptions of the former taxa(More)
Crocodyliforms serve as important taphonomic agents, accumulating and modifying vertebrate remains. Previous discussions of Mesozoic crocodyliform feeding in terrestrial and riverine ecosystems have often focused on larger taxa and their interactions with equally large dinosaurian prey. However, recent evidence suggests that the impact of smaller(More)
Exaggerated cranial structures such as crests and horns, hereafter referred to collectively as ornaments, are pervasive across animal species. These structures perform vital roles in visual communication and physical interactions within and between species. Yet the origin and influence of ornamentation on speciation and ecology across macroevolutionary time(More)
BACKGROUND Eolambia caroljonesa is the most abundant dinosaur in the lower Cenomanian Mussentuchit Member of the Cedar Mountain Formation of Utah, and one of the most completely known non-hadrosaurid iguanodontians from North America. In addition to the large holotype and paratype partial skulls, copious remains of skeletally immature individuals, including(More)
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