What are Some Different Types of Dinosaur?
Most broadly, there were two orders of dinosaurs in existence: bird-hipped and lizard-hipped. The bird-hipped dinosaurs (ornithiscians) consisted of diverse herbivores including Stegosaurus, Triceratops, Ankylosaurus hadrosaurs (duck-billed dinosaurs), and thick-headed dinosaurs such as Dracorex. The lizard-hipped dinosaurs (saurischians) included the theropods, which included every carnivorous dinosaur, and the sauropods, which were the largest animals ever to walk the Earth. The dinosaur evolved from archosaur ancestors in the middle Triassic period, about 230 million years ago, not long after the greatest mass extinction in the Earth’s history. Archosaurs are the group that includes modern-day birds and crocodiles, but at the time, they had a universally reptilian appearance. Common features of archosaurs include teeth set in sockets, special holes in the skull to reduce weight, and extra notches on the femur for muscle attachments. Dinosaurs are essentially just archosaur reptiles
