The Allokotosaur (Reptilia: Archosauromorpha) Assemblage From a Multitaxic Bonebed in the Sonsela Member (Jim Camp Wash Beds, Chinle Formation) at Petrified Forest National Park, U.S.A.

Allokotosaurian archosauromorphs (i.e., trilophosaurids and azendohsaurids) are known from Middle Triassic to Upper Triassic terrestrial deposits in Madagascar, Morocco, India, the United Kingdom, southeastern Canada, and the southwestern United States. In western Texas, trilophosaurids and malerisaurine azendohsaurids co-occur in Otischalkian sites, but numerous sites in the Chinle Formation-Dockum Group depobasin of Texas, New Mexico, and Arizona preserve either trilophosaurids or malerisaurines, blurring our understanding of the evolution of these groups and their potential biostratigraphic utility. Here we report an allokotosaurian assemblage from PFV 410 (the Kaye Quarry), a lowermost Revueltian locality in the upper Sonsela Member of the Chinle Formation at Petrified Forest National Park that preserves both trilophosaurid and malerisaurine azendohsaurid taxa, which indicates that these lineages may have co-occurred in the southwestern United States for ~10 million years during the Carnian to Norian. This locality is important because it pre-serves teeth of Trilophosaurus phasmalophos in a maxilla that may help resolve taxonomic uncertainty in that genus, and it shows that malerisaurines persisted at least for some time after the hypothesized Adamanian-Revueltian biotic turnover.