Isodontosaurus gracilis was named by Gilmore (1943). Its type specimen is AMNH 6647 (posterior portions of both rami with teeth) and is a 3D body fossil. Its type locality is Shabarakh Usu (AMNH loc. 12049), which is in a Campanian eolian sandstone in the Djadokhta Formation of Mongolia. It is the type species of Isodontosaurus.