Genus of clawed theropod dinosaurs that flourished in western North America during the Early Cretaceous period (144–99 million years ago). Deinonychus walked and ran on two legs, yet its killing devices, large sickle-like talons 5 in. (13 cm) long on the second toe of each foot, required it to stand on one foot while slashing at its prey with the other. Its long, outstretched tail was enclosed in bundles of bony rods that grew out of the tail vertebrae, making it very rigid. About 8–13 ft (2.4–4 m) long and weighing 100–150 lbs (45–68 kg), it had a large brain and was evidently a fast, agile predator.

This entry comes from Encyclopædia Britannica Concise.
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