During the Permian Period, which began 299 million years ago, the rainy, tropical jungle of the Carboniferous disappeared. The Permian world was one of dry scrublands and deserts. Large amphibians, which needed to spend time in the water, died out, while reptiles multiplied. Many reptiles evolved powerful jaws, enabling them to feed on tough desert plants.

Pelycosaurs

Some Permian reptiles, like Dimetrodon and Edaphosaurus, were three-metre-long (10-foot) giants. They belonged to a group of reptiles called pelycosaurs. Rising from their backs were “sails” of skin, held up by long, thin spines. These sails may have helped the animals heat up or cool down quickly.

At the end of the Permian Period, a great number of animals died out. More than two-thirds of land animals and plants disappeared. It was the biggest mass extinction in the Earth's history. Scientists do not know what triggered it, but extreme climate change probably led to the extinctions.