The Permian Period (299–252 million years ago) was the last part of the Paleozoic Era, when mammal-like reptiles like Dimetrodon and giant amphibians roamed the land, and early sharks and strange sea creatures lived in the oceans. The climate started warm and humid, but later became dry and harsh, turning many areas into deserts. It ended with 'the great dying', the biggest mass extinction in Earth’s history, wiping out most life.