About 251 million years ago, 90 percent of the Earth’s species became extinct. The mass extinction, called the “Great Dying” or the more scientific-sounding Permian-Triassic extinction event, made 96 percent of marine animals and 70 percent of land-dwelling animals extinct in just a few thousand years, and it took the earth as much as 10 million years to regain the biodiversity that it had lost. Researchers believe that they may finally know why the event occurred, but the theory is not without controversy.
There are several theories, including the possibility of a meterorite hitting the planet. Previously, most researchers believed that the Permian mass extinction was a result of a series of volcanic eruptions in what is now Siberia. These eruptions would have caused a dramatic rise in the amount of greenhouse gases which would have, in turn, killed off a bulk of species.
However, Daniel Rothman from the Massachusetts Institute of Technology is floating around a different theory. As he presented in a meeting for the American Geophysical Union, he believes that the mass extinction could have been caused by something much smaller. His theory is that the extinction was caused by a single strain of bacteria.