small, lightly built carnivorous dinosaur found as fossils from the Late Jurassic Period (146 million to 161 million years old) in North America. Ornitholestes is known from a nearly complete skeleton found in Wyoming, U.S. It was about 2 metres (6.6 feet) long, with a long skull, neck, and tail; the neck was apparently very flexible. The forelimbs were well developed and ended in three long clawed fingers, which indicates that Ornitholestes could catch quick and elusive prey. Its name means “bird robber,” but it probably ate small, speedy lizards (lizard) and even early mammals (mammal). The hind limbs were well developed, with strong running muscles. Some authorities have equated Ornitholestes and Coelurus, but they appear to be separate genera.