The Earth as it appeared near the middle of the Triassic Period (248 to 213 mya). All the major land masses are joined in a single "super-continent" called Pangaea. The climate is warming up from the Permian Ice Age to the tropical warmth of the later Mesozoic. Dinosaurs first appeared during the Triassic, evolving from the reptilian thecodonts. Most of the early dinosaurs were relatively small in size (for dinosaurs!) and tended to walk on their large hind legs. Map courtesy of Ronald C. Blakey at NAU.