What is a prehistoric animal?
Prehistoric animals are all organisms that walked—or swam, crawled, slithered, or flew—on Earth more than 5,500 years ago, before humans started recording history. The earliest known remains date to the Cambrian era, about 600 million years ago, although simple-celled organisms have been around much longer. Crustaceans, flying reptiles, dinosaurs, woolly mammoths, and saber-toothed tigers are just a few of the hundreds of millions of prehistoric animals that once lived on Earth. Paleontologists know about these animals by studying fossils, animal remains that have been preserved in rock.
