List of dinosaurs, with facts & information.. Dinosaur, the common name given to a group of reptiles, often very large, that first appeared roughly 245 million years ago and thrived worldwide for nearly 180 million years.
Dinosaurs are a diverse group of warmblooded reptiles [note 1] of the clade dinosauria.. They existed through most of the mesozoic era, first appearing early in the triassic period.