Theropods are a group of bipedal saurischian dinosaurs. Although they were primarily carnivorous, a number of theropod families evolved herbivory during the Cretaceous Period. Theropods first appeared during the Carnian age of the Late Triassic about 230 million years ago (Ma) and were the sole large terrestrial carnivores from the Early Jurassic until the close of the Cretaceous, about 65 Ma. Today, they are represented by the 9,300 living species of birds, which evolved in the Late Jurassic from small specialized coelurosaurian dinosaurs.
Among the features linking theropods to birds are the three-toed foot, a furcula (wishbone), air-filled bones and (in some cases) feathers and brooding of the eggs.