Guide to Dinosaurs

DINOSAURS WERE AMONG the most amazing and successful animals ever. From ancestors no bigger than dogs, they evolved into gigantic killers as heavy as elephants, plant-eaters several buslengths long, and nimble little creatures the size of chickens. While they ruled the land, no mammal larger than a domestic cat survived. Dinosaurs first appeared about 230 million years ago and flourished for an astonishing 165 million years. Then, 65 million years ago, they suddenly and mysteriously disappeared. By comparison, modern humans have inhabited the Earth for only about 100,000 years.