THEROPOD

any member of a suborder (Theropoda) of saurischian (reptile-hipped) dinosaurs. The theropods included all the carnivorous or predaceous dinosaurs except the staurikosaurs. They were the most differentiated group of saurischian dinosaurs, ranging in size from the chicken-sized Compsognathus, the smallest known adult dinosaur, which probably weighed 12 kg (24 pounds) to the huge Tyrannosaurus, which weighed 6 tons or more. Theropod remains have been recovered from the Late Triassic through the Late Cretaceous periods (from 230 to 66.4 million years ago) and from all continents except Antarctica. All the theropods were obligate bipeds. Their hind legs were dominant and designed for support and locomotion, while the forelimbs were shortened and had mobile hands, probably adapted for grasping and tearing prey. Despite the group's name, which means beast (i.e., mammal) foot, theropod feet usually resembled those of birds. Many scientists believe that all modern birds are descended from one line of small theropods.