Dinosaurs are a diverse group of reptiles that were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period (about 230 million years ago) until the end of the Cretaceous (about 66 million years ago). The extinction of most dinosaur species occurred during the Cretaceous–Tertiary extinction event. The fossil record indicates that birds evolved from theropod dinosaurs during the Jurassic period. Some of them survived the Cretaceous–Tertiary extinction event, including the ancestors of all modern birds. Consequently, in modern classification systems, birds are considered a type of dinosaur — the only group of which that survives until the present day.
Fossils and skeletons (examples)
Allosaurus fossil skull.
Brachiosaurus, Berlin Naturkundemuseum.
Tyrannosaurus (named "Sue"), FMNH.
Gargoyleosaurus, Denver Museum of Nature and Science.
Microraptor, with preserved feathers.
See more: Category:Dinosaur skulls
Clutch of round eggs named Oolithes spheroides, Location: Senckenberg-Museum, Frankfurt am Main