Full reference: H. J. Cook. 1934. New artiodactyls from the Oligocene and Lower Miocene of Nebraska. American Midland Naturalist 15(2):148-165
Sister taxa: none
Type specimen: No. HC500, a maxilla (left maxilla with P3 to M3). Its type locality is Syndyoceras Quarry, which is in a Harrisonian terrestrial horizon in the Harrison Formation of Nebraska.