CARNOSAUR

any of the large carnivorous dinosaurs belonging to the infraorder Carnosauria (suborder Theropoda). The carnosaurs were a branch of theropod dinosaurs that evolved into predators of large herbivorous dinosaurs. The carnosaurs were thus in contrast with the theropod dinosaurs known as coelurosaurs, which were smaller, lightly built, swift-running predators. The carnosaurs are believed to have diverged from the coelurosaur line in the Late Triassic Period (230 to 208 million years ago), and they had become the main predators of large animals by the Early Jurassic (208 to 187 million years ago). Carnosaurs were massively built bipeds with short necks, large skulls, and wide, gaping mouths equipped with formidable teeth. The earlier forms are typified by Megalosaurus, which was 9 m (30 feet) long and lived during the Jurassic. The carnosaurs developed progressively larger forms, and the Allosaurus of the Late Jurassic, at 12 m in length, eventually gave way to Tyrannosaurus of the Late Cretaceous Period (97.5 to 66.4 million years ago). Tyrannosaurus was the largest of all carnosaurs, reaching lengths of 15 m, and was the largest terrestrial carnivore ever known. The carnosaurs became extinct at the end of the Cretaceous.