VERTEBRATE REMAINS FROM THE LATE CRETACEOUS OF SOUTH DAKOTA AND MINNESOTA

An assemblage of vertebrate remains from the late Cretaceous (Turonian) of southeastern South Dakota on the border with Minnesota is described as a poorly known and incomplete fauna. The Carlile Formation in this area unconformably overlies fractured and eroded Pre-Cambrian granite that existed as coastline and offshore islands during the late Cretaceous. The coastal area provided a shallow-water habitat for a rich marine vertebrate fauna that included a variety of fishes and pelagic reptile, such as turtles, plesiosaurs, and mosasaurs. Commercial quarrying of the underlying granite has exposed sediments of the fossil-rich Carlile Shale in several in Grant County, South Dakota, which are the principal collecting localities. In addition to this fauna, four similar age plesiosaur specimens from the Carlile, Coleraine, and Windrow (Ostrander Member) formations from widely separated localities in southwestern, north-central, and southeastern Minnesota respectively, are described as the first records from the state. Dinosaurian elements are also included in the discussion as a sampling of the terrestrial forms that were deposited in the shallow-water marine sediments of the Carlile and Coleraine Formations. The sea turtle Desmatochelys and the estuarine crocodile Terminonaris (= Teleorhinus) are also discussed in terms of their paleoenvironmental implications.