Before the Dinosaurs - Pelycosaurs, Archosaurs, and Therapsids
Dinosaurs weren’t the first four-legged reptiles to prosper on land. The Carboniferous and Permian periods witnessed a large variety of "primitive" terrestrial reptiles, the pelycosaurs, archosaurs and therapsids, many of which boasted surprisingly advanced features.
How Did Dinosaurs Evolve?
Like all living creatures, dinosaurs evolved from preexisting ancestors, in this case a family of prehistoric reptiles known as archosaurs (which also spawned pterosaurs and prehistoric crocodiles). Here's an overview of current thinking about dinosaur evolution.
The First Dinosaurs
Some time during the middle to late Triassic period, about 230 million years ago, the first true dinosaurs evolved from their archosaur ancestors. Here's everything you need to know about these early theropods, including such crucial genera as Eoraptor and Herrerasaurus.
How Are Dinosaurs Classified?
How do paleontologists classify dinosaurs? Here’s a detailed guide to the major orders, suborders and infraorders, according to the state of current research, including the crucial distinction between ornithischian ("bird-hipped") and saurischian ("lizard-hipped") dinosaurs.
Dinosaurs and Creationists
Creationists don't believe in evolution, and they insist that the earth is only a few thousand years old. That doesn't mean, however, that they don't believe in dinosaurs--but they do propose some strange theories, including the odd notion that dinosaurs coexisted with human beings.