Swiss paleontologists have found that approximately 250 million years ago, a million years after the famous Permian extinction of animals and plants there was another similar event, which destroyed a large number of plants.
“We don’t yet know what was the reason of this disaster. On the other hand, indirect indicators show that there is a connection between this event and the most powerful eruptions of volcanoes in that part of the Earth in the early Triassic period, which later became the modern Siberia,” said Hugo Bucher (Hugo Bucher from the University of Zurich (Switzerland).
It tells Bucher, they discovered traces of the mass extinction of plants and hints at the existence of another such event in the early Triassic period allow us to call it a kind of “era of mass extinctions”, and also explain why the flora and fauna of the Earth has spent an unusually long time, several million years to recover from the “great” Permian extinction.
Scientists came to this conclusion by studying a 400-meter layer of sedimentary rocks on the territory of modern Greenland, which formed during the Permian extinction that occurred 252 million years ago, and the first age of the Triassic period.
Bucher and his colleagues tried to uncover one of the most puzzling characteristics of the Permian extinction – why plant species composition remained extremely scarce in the first few million years after its completion, despite the release of ecological niches, and the almost complete absence of the usual “natural enemies – herbivores.
The answer to this riddle, scientists searched for two things that could be “read” in the fossils and rocks of the Triassic – how varied the concentration of heavy carbon-13, and the structure and size of pollen grains and spores of plants. The proportion of isotopes of carbon, as the researchers explain, are a direct indicator of how many plants grew on Earth at the time, and the changes in “sets” of pollen and spores may indicate a sharp or a gradual change in climate and plant species composition.
Both of these indicator revealed an unexpected thing. It turned out that approximately 500 thousand – million years after the Permian extinction there was another disaster. She actually destroyed almost all the plants that grew at that time in Greenland, and replaced them with entirely new types of flora for a thousand years, a blink in geological and evolutionary terms. This “changing of the guard” was accompanied by a fall in the volume of the biomass, which indicates that another mass extinction, which we previously had no idea.
This event, as shown by similar studies that team Bucher conducted in Australia and in Pakistan, has affected not just Greenland, who was at that time closer to the equator, but the whole Earth.
The cause of this extinction, according to Bucher was the same process that caused the Permian extinction – a massive outpouring of magma in Eastern Siberia and the saturation of the atmosphere volcanic gases. Apparently, they caused global warming and moved the Earth into “greenhouse mode,” as this new extinction was dominated by cold and arid climate of the Permian, followed by a damp and hot climate of the Mesozoic era.
The fact that the boundary between the Permian and Triassic was not one but a series of at least two or more extinctions, good fit and explains not only slow the recovery of the flora, but also strange non-simultaneous extinction of several groups of marine molluscs and other marine life. Thus, the whole history of the evolution of life at the turn of the Permian and Triassic periods needs to be revised, conclude the authors.
