TAXONONOMIC REVISION AND PALEOECOLOGY OF “THE CAPTAIN”, A UNIQUELY DERIVED TYLOSAURUS KANSANESIS SPECIMEN

During the late Cretaceous (Coniacian, 87 – 82.5 ma) when the western interior seaway was in full flooding stage from the Gulf of Mexico up to Arctic Circle in North America. A remarkable event in terms of biodiversity of the Niobrara formation occurred at this time. This event set forth physical drivers that led to the development of the various squamate subfamilies within Mosasauroidea and the parafamily of Russellosaurina. The one subfamily in particular raises interesting implications within interpretation of their taxonomic placement, the Tylosaurines. Within the subfamily of Tylosaurinae sits four apex predators all ranging from the various stratigraphic times in the upper Cretaceous they are Tylosaurus, Taniwhasaurus, and Hainosaurus. Based on new evidence of a well preserved specimen of Tylosaurus kansasensis recovered from between MU2 – MU5 in the Niobrara Formation of central Kansas a unique set of characters offers a differential diagnosis of the animal based on cranial and post cranial morphology that can maintain the taxonomic stability found within Tylosaurinae. This specimen also provides information on the paleoecologcal role of Tylosaurus based on comparative anatomy and current studies of WIS ecology.