Deinonychus (Dine-ony-cuss) was a small carnivorous dinosaur that lived during the early Cretaceous Period of North America, 119 to 93 million years ago. It was approximately 7 feet long and stood 3 to 4 feet high. It was a close relative of Velociraptor (Vel-ah-si-rap-tor), made famous by the Jurassic Park movies. In fact, the "Velociraptors" shown in those films are not Velociraptor at all, but are actually Deinonychus (however, they have been greatly enlarged to make them appear more menacing).
Deinonychus was an agile hunter with a stiff, counterbalancing tail, and a wicked spur-like talon on the hind foot. Only two toes were used for running as the large claw remained retracted when not being used as a weapon. Presumably, Deinonychus grasped its prey with its well-developed front limbs, while slashing it with its hook-like hind claw.
Skeletal characteristics of Deinonychus are strongly reminiscent of birds, suggesting a bird - dinosaur evolutionary relationship. Because of this, Deinonychus is occasionally pictured as having feathers!
Deinonychus had a relatively large bird-like brain and, thus, may have been capable of sophisticated behaviors. However, it is very unlikely that this dinosaur was as clever as depicted in the movies (note that the phrase "bird brain" does not suggest intellect).