In general, scientists believe that the main reason for the mass extinction about 250 million years ago, at the end of the Permian period, was the Siberian volcanoes, which emitted greenhouse gases. The gases caused severe warming, which in turn led to the extinction of 80% of all marine species, as well as many terrestrial species.
Until now, scientists have been unable to explain exactly how the heat caused all these deaths. New research shows that high temperatures accelerate the metabolism of microorganisms, creating deadly conditions. Scientists said that microbes began to release hydrogen sulfide, a gas that smells like rotten eggs and is poisonous to animals. Thus, the Earth 250 million years ago was not the most fragrant place.