The Permian 286 to 245 Million Years Ago The Permian period lasted from 286 to 245 million years ago and was the last period of the Paleozoic Era. The distinction between the Paleozoic and the Mesozoic is made at the end of the Permian in recognition of the largest mass extinction recorded in the history of life on Earth. It affected many groups of organisms in many different environments, but ...

News Release from the University of Washington ...

Synapsida: Systematics Synapsid classification has undergone tremendous change in recent years; most of the traditional groupings have been discovered to be paraphyletic. To represent this, we have used multiple lines drawn to paraphyletic groups in the cladogram above. Except for the Mammalia, all synapsid groups are extinct. Current hypotheses about early synapsid diversification suggest that ...