An extinct terrestrial reptile belonging to a group that arose some 225 million years ago and constituted the dominant land animals of the Jurassic and Cretaceous periods, 190–65 million years ago. There were two orders. The Ornithischia were typically quadrupedal herbivores, many with heavily armoured bodies, and included Stegosaurus, Triceratops, and Iguanodon. They were all characterized by birdlike pelvic girdles. The Saurischia included many bipedal carnivorous forms, such as Tyrannosaurus (the largest known carnivore), and some quadrupedal herbivorous forms, such as Apatosaurus (Brontosaurus) and Diplodocus. They all had lizard-like pelvic girdles. Modern birds evolved from saurischian ancestors (see aves) and belong to a clade called theropods, predatory dinosaurs that shared birdlike traits. Many of the herbivorous dinosaurs were amphibious or semiaquatic.

http://www.nhm.ac.uk/discover/dino-directory/index.html A Dino Directory produced by the Natural History Museum, London