The Post-Permian Period is a period of time in Earth's history that followed the Permian Period and preceded the Triassic Period. It is also known as the Late Permian or Upper Permian and lasted from about 252 million to 201 million years ago. During this time, the Earth experienced a mass extinction event, which wiped out over 90% of marine species and 70% of terrestrial species. This event is considered to be the largest mass extinction in Earth's history.