Deinonychus antirrhopus ("counterbalancing fearsome claw") is a wolf-sized, carnivorous dromaeosaurid dinosaur class from the Early Cretaceous Clovery Formation of Montana. Its name, "Terrible claw", refers to the enormous, sickle-shaped talons on the second toe. These claws were almost certainly held retracted while the dinosaur walked on the third and fourth toes. It was usually thought that Deinonychus would kick with the sickle claws to cut at its prey, but recent tests on reconstructions of alike velociraptor talons propose that the claw was used to stab, not slash. Like with all dromaeosaurids the tail was stiffened by a sequence of elongated bones (not tendons).


Based on the group of a number of Deinonychus skeletons in a single quarry — several hundred Deinonychus bones were exposed by paleontologist John Ostrom and Grant E. Meyer in 1964 in southern Montana — it has been speculated that Deinonychus lived in packs. This is quite likely, but it is difficult to prove or disprove this idea. Shed teeth of Deinonychus are often established alongside skeletons of the ornithopod dinosaur Tenontosaurus, representative that it fed on them, and perhaps hunted them.

Deinonychus Dinosaur

John Ostrom named and described Deinonychus, and the detection of this clearly active, agile predator did much to change the scientific (and popular) beginning of dinosaurs and open the door to conjecture that dinosaurs may have been warm-blooded.

Several years later, Ostrom noted similarities between the hand of Deinonychus and birds, which led him to revitalize the hypothesis that birds are descended from dinosaurs. Thirty years later, this thought is almost universally accepted. Finds of related dinosaurs from China, such as Sinornithosaurus and Microraptor point to that this dinosaur almost certainly bore feathers. Other relatives include Velociraptor, Utahraptor, and Dromaeosaurus.

A skeleton of Deinonychus can be seen on show at the American Museum of Natural History or the Harvard Museum of Comparative Zoology. The American Museum and Harvard specimens are from a dissimilar locality than the Yale specimens which Ostrom described, and the claws are dissimilar shapes (Ostrom 1976). This raises the option that the two are, in fact, different species or even different genera.

Deinonychus Facts:
Name: Deinonychus
Size: Skull length: 410 mm (16 in)
Total length: 3 m (10 ft)
Hip height: 1.2 m (4 ft)
Weight: 80 kg (175 lb)
Main Facts: Renamed as "Terrible claw" .Its tail was stiffened by a sequence of elongated bones (not tendons).