New fossils from Tanzania reveal the rapid diversification of Archosauria

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New fossils from Tanzania reveal the rapid diversification of Archosauria.Christian A. Sidor (PI)Sterling J. Nesbitt (Senior Personnel)This grant supports a two-year postdoctoral research associate position for Sterling J. Nesbitt at the University of Washington, under the supervision of Christian A. Sidor (PI). Sidor and Nesbitts recent fieldwork in southern Tanzania has yielded a large collection of archosaur fossils from the Middle Triassic (approximately 240 million years ago). Living archosaurs include birds and crocodiles, but extinct members of this group encompass numerous taxa like aetosaurs, erpetosuchids, and notably, dinosaurs and their close relatives. Utilizing the new collection of fossils, Sidor and Nesbitt will collaborate to describe several species and interpret each in terms of its position on the archosaur family tree. More specifically, they will reanalyze Parringtonia (which was initially named in 1939), provide a complete anatomical description of the dinosauriform Asilisaurus (which they announced in 2010), and describe a new, aetosaur-like taxon and a new rauisuchian. Sidor and Nesbitt will also examine the Tanzanian archosaur fauna as a whole, by revising the biostratigraphy of the archosaur-bearing strata, and by gauging how the group diversified after the Permian-Triassic mass extinction in the Ruhuhu Basin of Tanzania relative to other contemporaneous geologic basins. Vertebrate paleontology fascinates the public. As part of the broader impact goals of this project, Sidor and Nesbit will develop a temporary display at the University of Washingtons Burke Museum, to highlight some of the best specimens from Tanzania and to explain how fossils and rocks can inform scientists about past climates (e.g., the Triassic hot-house world lacked polar glaciers). Sidor and Nesbitt will also curate the collection of archosaur fossils in anticipation of its repatriation to the National Museum of Tanzania in Dar es Salaam. However, research-quality casts will be created and retained at the Burke Museum.