This is a complicated name which means oetwo crested lizard. This is one of the oldest predatory dinosaurs, predating the T-Rex. It was up to 25 feet long but weighed only 880 pounds. The fossils of these hunting dinosaurs are found in the western United States, which came into existence 150 million years after the Dilophosaurus. This is easy to identify by the two brightly colored crests on its head.