For decades, scientists have conducted research centered around the five major mass extinctions that have shaped the world we live in. The extinctions date back more than 450 million years with the Late Ordovician Mass Extinction to the deadliest extinction, the Late Permian extinction 250 million years ago that wiped out over 90 percent of species.
Over the years, scientists have figured out the main causes of the mass extinctions, which include massive volcanic eruptions, global warming, asteroid collisions, and acidic oceans as likely culprits. Other factors sure to play a part include methane eruptions and marine anoxic events – when oceans lose life-supporting oxygen.