Any species of bipedal, carnivorous saurischian in the suborder Theropoda. The chicken-sized Compsognathus,the smallest known adult dinosaur, probably weighed 2–4 lb (1–2 kg); the tyrannosaurs weighed tons. The theropods also included Allosaurus, Deinonychus, Megalosaurus, Oviraptor, and Velociraptor. Theropod remains recovered have been from the Late Triassic through the Late Cretaceous Epoch (227–65 million years ago) from all continents except Antarctica. Their well-developed hind legs provided support and locomotion; their short forelimbs had mobile hands, probably for grasping and tearing prey. Despite the group's name, which means beast (i.e., mammal) foot, theropod feet usually resembled those of birds. It is widely believed that all modern birds are descended from one line of small theropods.