Permian-triassic extinction event 1

Gorgonopsians were among those animals that did not survive the Permian–Triassic extinction

The Permian-Triassic extinction event was a global catastrophe that wiped out 96% of all life on Earth.  It began during the Carboniferous period because the trees were dying and were storing carbon dioxide in the ground.  This went on for millions of years into the Permian period along with the methane-producing bacteria in the ocean.  As methane and carbon dioxide built up in the ground and seas, they caused massive climate change when massive volcanism took place.  The extreme amounts of carbon dioxide in the air coupled with clouds of ash dried the surface of the Earth and methane deposits in the ocean suffocated the sea life.  All blastoid echinoderms, trilobites, and eurypterids were wiped out along with all Acanthodian fish and large amounts of anapsids, synapsids, and diapsids. Small amphibians, reptiles, and therapsids thrived during the early Triassic until the Archosauromorphs, such as dinosaurs and crocodiles, appeared which put the diapsids on top on land and the Mesozoic sea life explosion diversified the diapsids of the seas.  Anapsids would never again be as diverse as before the Permian-Triassic extinction event and synapsids would evolve into mammals as time went on.