A new phytosaur (Archosauriformes, Phytosauria) from the Lot’s Wife beds (Sonsela Member) within the Chinle Formation (Upper Triassic) of Petrified Forest National Park, Arizona

ABSTRACT

A new phytosaur taxon from Petrified Forest National Park, Arizona, is here described based on cranial material from a single individual. This specimen previously was included in an extensive phylogenetic analysis, and it was found to possess a combination of character states that differs from all known phytosaur taxa in addition to two autapomorphies within the braincase and an autapomorphy of the mandible. The new taxon adds to the taxonomic diversity recognized from the Sonsela Member of the Chinle Formation. The continued increase in phytosaur diversity emphasizes the need to more accurately characterize and identify taxa within a phylogenetic systematic context in order to produce a more refined signal for biostratigraphic correlations, biochronologic inferences, and faunal dynamics during the Late Triassic.

ACKNOWLEDGMENTS

This project was part of a thesis completed in partial fulfillment of an M.Sc. degree at the University of Iowa under the supervision of C. Brochu, K. Padian, and J. Adrain. Discussions with C. Bell, K. Claeson, J. Clarke, S. Drumheller, R. Irmis, S. Nesbitt, J. Olori, W. Parker, T. Rowe, and A. Turner clarified and focused the manuscript. M. Norell, C. Mehling, T. S. Williams, W. Parker, K. Padian, P. Holroyd, T. Rowe, L. Murray, B. Simpson, S. Chatterjee, B. Mueller, H.-D. Sues, and G. Gunnell provided access to specimens. N. Fraser, an anonymous reviewer, E. Rayfield, and P. Barrett provided helpful suggestions and greatly improved the quality of the manuscript. The American Museum of Natural History Theodore Roosevelt Grant, the University of California Museum of Paleontology Doris and Samuel P. Welles Fund, the Paleontological Society Stephen Jay Gould Grant, and the University of Iowa Littlefield Fund provided funding for this project.

Handling editor: Emily Rayfield