Article: A new rhynchosaur from the Upper Triassic of West Texas, and the biochronology of Late Triassic rhynchosaurs

A new rhynchosaur (Reptilia, Diapsida), Otischalkia elderae, from the lower Dockum Group of West Texas is represented by two premaxillary fragments, two femora, and two humeri. The lower Dockum is early late Carnian (Paleorhinus biochron) in age. Other Late Triassic rhynchosaurs are: indeterminate hyperodapedontines from the Popo Agie Formation of Wyoming, Isalo II beds of Madagascar and an undescribed stratigraphic unit in Tanzania; Scaphonyx from the Wolfville Formation of Nova Scotia, Santa Maria, and Caturrita Formations of Brazil and the Ischigualasto Formation of Argentina; Hyperodapedon from the Maleri Formation of India and the Lossiemouth Sandstone Formation of Scotland. These occurrences of Late Triassic rhynchosaurs are of early late Carnian age. Late Triassic rhynchosaur distribution is largely controlled by the facies that are preserved at different localities. Rhynchosaurs are common in more terrestrial faunas that contain few or no phytosaurs, whereas rhynchosaurs are rare in semiaquatic faunas dominated by phytosaurs.