Deinonychus (genus Deinonychus), Encyclopædia Britannica,
Inc.long-clawed carnivorous dinosaurs that flourished in western
North America during the Early Cretaceous Period (145.5 million
to 99.6 million years ago). A member of the dromaeosaur group,
Deinonychus was bipedal, walking on two legs, as did all
theropod dinosaurs. Its principal killing devices were large
sicklelike talons 13 cm (5 inches) long on the second toe of
each foot. The slender, outstretched tail was enclosed in
bundles of bony rods. These extensions of the tail vertebrae
were ideal for helping the animal maintain balance as it ran or
attacked prey.  Deinonychus was the model for the “raptor”
dinosaurs of the motion picture Jurassic Park (1993). The name
raptor has come to apply to dromaeosaurs in general as a
contraction for Velociraptor, a genus of dromaeosaur that was
considerably smaller than Deinonychus. However, the term raptor
(from the Greek word for “seize” or “grab”) is more correctly
applied to birds such as hawks and eagles, wh