Anatomy: Deinonychus had a curved, flexible neck and a big head with sharp, serrated teeth in very powerful jaws. Each of its three fingers on each hand had large, sharp, curved claws. It had four-toed feet; the second toe had a 5-inch (13-cm) sickle-like claw, and the other toes had smaller claws. Its long tail had bony rods running along the spine, giving it rigidity; the tail was used for balance and fast turning ability. Deinonychus had a relatively large brain and large, keen eyes. This dromaeosaurid theropod had a relatively large brain for a dinosaur.

Fossils and Name: Deinonychus was first found by Grant E. Meyer and John H. Ostrom in southern Montana (in the western United States) in 1964. Deinonychus antirrhopus was named by Ostrum in 1969. More than eight Deinonychus fossils have been found in Montana, Utah, and Wyoming, USA.