The largest ever mass extinction on earth may have been triggered by poisonous volcanic gas which erupted in Siberia 250 million years ago , according to a new research. This must have happened before dinosaurs came into existence, towards the Permian era's end, when over two-thirds of amphibians and reptiles were wiped out.
Possibilities like a deep sea methane release, an asteroid hitting the earth, or a greenhouse effect were contemplated by scientists as reasons for the mass extinction.
According to Discovery News, the eruption was the earth's biggest outpouring as the crust split and torrents of lava were released. They covered vast swaths of land in present-day Siberia and created the Siberian Traps, a large area of igneous rocks around the city of Tura.
New evidence for the volcanic gas hypothesis comes from a unique set of molecules preserved in rocks from the Dolomite mountains in Italy. Dating from the time of the extinction, the molecules are the remains of polysaccharides, large sugar-based structures common in plants and soil. The chemistry of the rocks revealed that although the polysaccharides are remains of marine sediments, they are derived from land, supporting the theory that a massive soil erosion resulting from destruction of land vegetation caused them to end up in the sea.
The excessive supply of soil materials to the oceans provides a direct link between terrestrial and marine ecological crises, suggesting that the ecosystem collapse on land could have contributed to the end-Permian marine extinctions.
The terrestrial ecosystem was the first to suffer. The continent-wide nature of the event implies that it was caused by something in the atmosphere, Sephton said. The soil crisis could have caused a worldwide expanse of uninhabitable low-oxygen conditions in shallow marine waters, a condition similar to the oxygen-depleted waters found today in the Gulf of Mexico's dead zone, said the researchers.