The mass extinction that hit Earth late Permian Period, 250 million years ago, before the reign of the dinosaurs, wiped out most of the world’s life forms. By some estimates, about 96 percent of all marine species and 70 percent of land species perished.
Typically, an extinction of such magnitude is followed by a period of scarcity of biodiversity during which no new species, and that usually takes tens of thousands of years. In this case, the lack of biodiversity phase, during the first stage of the Triassic Period, which began after the extinction, lasted no less than five million years, or even ten million by some estimates.
A joint study conducted by experts from the University of Leeds in the UK and University of Geosciences Wuhan in China, in collaboration with Friedrich-Alexander University of Erlangen-Nuremberg in Germany, shows that the cause of the prolonged absence of wealth biological was the rising temperatures in the tropics to lethal levels: about 50-60 ° C on the ground, and 40 °C at the sea surface.
Global warming was highlighted as a decisive cause of this mass extinction at the end of the Permian, but the new study by Yadong Sun team is the first to show that the extreme temperatures prevented, for millions of years, the life in equatorial latitudes as we understand it today there recommence.
The existence of a dead zone for millions of years, at the time when the Earth was a giant continent called Pangea, led to many anomalous situations. There was a lot of moisture in the tropics but almost nothing grew there. No forest was developed, essentially only shrubs and ferns. We could not find any fish or marine reptile in the tropics, only certain crustaceans and molluscs, and there was virtually no land animal because its high metabolic rate made it impossible to deal with extreme temperatures. Simply heat the Dead Zone was too high for many of the forms of life could survive there.
Only the Polar Regions acceptable provided a refuge for the scorching heat that covered much of the planet.
On the trigger for the catastrophe that led to the extinction, various theories have been proposed, many of which include principal mechanism colossal volcanic eruptions, which, among other effects, caused a global climate change.