A new baenid, "Trinitichelys" maini sp. nov., and other fossil turtles from the Upper Cretaceous Arlington Archosaur Site (Woodbine Formation, Cenomanian), Texas, USA

The Arlington Archosaur Site (AAS) is a Cenomanian (93-99 Mya) fossil locality in the Woodbine Formation of Texas. Woodbine deposits form primarily terrigenous near shore and shallow marine depositional systems, including shelf, deltaic, and fluvial environments. The AAS is the oldest Upper Cretaceous unit in the Gulf Coastal Plain, and the most complete fossil ecosystem discovered in southwestern Appalachia. It preserves a freshwater/brackish wetland situated in a low-lying coastal plain. The site contains diverse fossil vertebrate and invertebrate faunas and abundant carbonized plant material. The taphonomy of the site is complex, frequently resulting in fragmentary specimens due to a mixture of environmental transport, biological accumulation, pervasive crocodyliform predation, massive storms, wildfires, and widespread flooding events. Numerous new reptilian taxa (particularly crocodyliform) have been recently described, but turtles from the site have not been taxonomically identified. This study documents fossil shell material of AAS turtles, most of which were previously unknown from the site. Results include a new baenid species, "Trinitichelys" maini sp. nov., numerous elements of the helochelydrid Naomichelys, a small trionychid, and a bothremydid. Insights from the turtle faunas at the AAS contribute to our growing understanding of the coastal ecosystems of southwestern Appalachia at the beginning of the Upper Cretaceous.