COELOPHYSIS

genus of small carnivorous dinosaurs found as fossils in Late Triassic rocks (230 to 208 million years ago) of North America. Coelophysis was a primitive theropod of the ceratosaurian infraorder. It was about 2.5 m (8 feet) long and was very light, weighing only about 18 to 23 kg (40 to 50 pounds), owing to its hollow bones. It had a long, slender neck, tail, and hind legs, and a long, narrow head equipped with many sharp teeth. In general the coelurosaurs were primitive bipeds capable of rapid movement. Coelophysis and the other coelurosaurs were agile, lightly built predators who possibly fed on other small reptiles and the very early mammals. This group is representative of the basal stock from which the sauropod dinosaurs developed; clear relationships are evident in the structure of the pelvis. The coelurosaur known as Podokesaurus was related to or congeneric with Coelophysis, though smaller in size (about 1.5 m long).