Coelphysis is one of the best known early dinosaurs. This is because of an abundance of fossils and skeletal remains. These 10 foot long, 65 pound predators lived over 220 million years ago. They were once thought to be cannibals, but this has been dismissed. Coelphysis was certainly a meat-eater though. It's needle like teeth were perfect for catching small prey. Coelphysis lived in North America.