Dinosaurs

Dinosaurs are a diverse group of animals that were the Dominate terrestrial verterbrates for over 160 million years,from the late triassic period (about 65 million years ago).When the Cretaceous paleogene extinction event led to the extinction of most dinosaur species at the close of the Mesozoic era.The fossil record indicates that birds envolved within theropod dinosaurs during the jurrasic period.Some of them survived the Cretaceous Paleogene extinction event,including the ancestors of all modern birds.Consequently,in modern classification systems,birds are considered a type of dinosaur-the only group to survive a present day