The Compsognathus, family Compsognathidae, is a small carnivorous dinosaur about 3 feet long and lived 150 million years ago. This biped had long hind legs as well as an even longer tail essential to his balance when moving. His long, thin hind legs allowed him to reach a maximum speed of 40 miles per hour. His name, which means "delicate jaw," comes from his narrow, long head, ending in a slender snout.