Permian Mass Extinction

The Permian Mass Extinction (also called the Permian-Triassic Extinction Event or the Great Dying) was the largest mass extinction event the planet Earth ever saw. It occurred 250 million years ago at the conclusion of the Permian & ended the Paleozoic Era. This also ended at the beginning of the Mesozoic Era.

Causes
Scientists in the Great Inventing era assumed the number one reason that animals went extinct in the first place was due to massive volcanism in Siberia, a region of the Southern Oval. This prediction was assumed true since scientists could not find much evidence to contradict their prediction & the little evidence they had supported their theorys. The lack of evidence was caused by the fact that Siberia was too far south to reach, was remote due to large mountain ranges created from it's collision with the Southern Oval & was too close to the polar ice caps for any warmth.

Volcanism
250 million years ago, the mantle of Earth caused a flood basalt eruption in Siberia. The Siberian eruptions drove two species that grazed the plains at the time extinct: Scutosaurs & gorgonopsids. 10,000 miles away on the other side of Gondwana, nothing changed. But over time, it appeared to be snowing, yet the temperature was 70 degrees. The ash that was a fallout of the Siberian eruptions fell to Earth miles away & burned everything it touched. It also mixed with clouds & became sulfuric acid.

Anoxia
In the oceans, the heated atmosphere from the Siberian eruptions triggered an anoxic event, which the oceans were stripped of oxygen, causing most marine life to go extinct. The only things that existed in the water were blooms of pink algae composed of dinoflagellates. At the bottom of the seabed, methane that was frozen escaped as bubbles & headed into the atmosphere, raising temperatures & turning the atmosphere deadly.

Plate tectonics
5 million years later, in the Triassic Period, the plates began to change & the supercontinent Gondwana tore apart into massive clumps of land. 240 million years ago, the plate directions reversed & Siberia, Laurentia, the remains of Gondwana & other areas of Earth collided to become the last supercontinent, Pangaea, which stretched from pole to pole.

Marine regression
Because of the anoxia in the oceans & the constant movement of Earth's plates, the ocean levels fell & parts of the sea floor were exposed.

Terrestrial life
Ottsels, which were introduced in the Middle Pennsylvanian, miraculously survived & was one of the many mammals that lived in the Mesozoic.

Marine life
Trilobites, which had thrived in the oceans since the Cambrian, disappear.