A NEW THEROPOD DINOSAUR FROM THE LOWER CRETACEOUS OF MONTANA

Abstract

Deinonychus antirrhopus, a new genus and species of theropod dinosaur is described from the Cloverly Formation (Lower Cre taceous) of southern Montana. The species is characterized by a highly specialized pes bearing a very large, trenchant claw on digit II, a highly raptorial manus with a very mobile carpus, and a specialized caudal series with extremely long prezygapophyseal and chevron rods. The new species is closely related to Dromaeo-saurus albertensis, which features similar specialization of the second pedal digit, and is referred to the family Dromaeosauridae (=Dromaeosaurinae Matthew and Brown, 1922). Other species with comparable pes structure that may be referred to this family are Stenonychosaurus inequalis, Velociraptor mongoliensis and Saurornithoides mongoliensis.