Prehistoric animals are creatures that lived millions of years ago, long before humans existed. They include a wide variety of species, such as the mighty Tyrannosaurus rex, the enormous woolly mammoth, and the flying pterosaurs. These animals roamed the Earth during different geological periods, including the Triassic, Jurassic, and Cretaceous. Many prehistoric animals adapted to their environments in unique ways. For example, some developed thick fur to survive in cold climates, while others had sharp teeth and claws for hunting. Fossils, which are the preserved remains of these animals, help scientists learn about their lives and the ecosystems they inhabited.