How are dinosaurs related to dragons?

Dinosaurs and lizards both belong to a branch of reptiles called diapsids, which emerged in th early Permian period. In the early Triassic period the diapsids split into two main groups: archosaurs and lepidosaurs. The archosaurs were the ancestors of dinosaurs, pterosaurs (flying reptiles), and crocodilians. The lepidosaurs were the ancestors of lizards, snakes and a third, nearly extinct branch called sphenodonts.