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Monday, March 20, 2023

Discovered the causes of the first mass extinction on Earth

Fossil prints in Australia. (Photo: Scott EvansEuropa Press)

Fossil prints in Australia. (Photo: Scott EvansEuropa Press)

A new reason to take climate change even more seriously. A new study by geobiologists at Virginia Tech attributes the first known mass extinction of animals to a decline in global oxygen availability. These days COP27 is being held in Cairo, which seeks a new global agreement against the effects of destruction of the natural environment.

The research, published in PNAS, refers to the loss of 80 percent of the animals that existed at the end of the Ediacaran period, about 550 million years ago.

Scott Evans, a postdoctoral researcher in the Department of Geology, said, “This included the loss of many different types of animals, however, whose body plan and behavior indicate they are dependent on significant amounts of oxygen, particularly affected Has happened.” A statement and study author. “This suggests that the extinction event was environmentally controlled, like all other mass extinctions in the geologic record.”

Environmental changes, such as global warming and deoxygenation events, can lead to mass extinctions of animals

“Environmental changes, such as global warming and deoxygenation events, can lead to mass animal extinctions and deep ecosystem disruption and reorganization,” said co-author Shuhai Xiao, a professor of geology.

“This has been shown repeatedly in studies of Earth history, including this work on the first documented extinction in the fossil record. This study tells us about the long-term impact of current environmental changes on the biosphere,” Xiao said. Told.

What exactly is causing the drop in global oxygen? It is still up for debate. “The short answer to how this happened is that we don’t really know,” Evans said. “It could be any number and combination of volcanic eruptions, tectonic plate movement or asteroid impacts, but what we see is that extinct animals are responding to a decline in global oxygen availability.”

In an unrelated study, scientists at Virginia Tech recently found that anoxia, a decrease in oxygen availability, is affecting the world’s freshwater. cause? Water warming due to climate change and more polluting runoff from land use.

Hot water reduces the oxygen-carrying capacity of fresh water, while the breakdown of nutrients in runoff by freshwater microbes absorbs the oxygen.

This new and first mass extinction of animals was caused by a major climate change

“Our study shows that, as with all other mass extinctions in Earth’s past, this new and first mass extinction of animals was caused by major climate change, yet one in a long line of warning stories. And that demonstrates the dangers of our current climate crisis to animal life,” said Evans, a geobiology fellow at the Agauran Institute.

The Ediacaran period spanned about 96 million years, spanning both sides until the end of the Cryogenous period 635 million years ago and the beginning of the Cambrian period 539 million years ago. The extinction event occurs just before a significant break in the geological record, from the Proterozoic eon to the Phanerozoic eon.

other mass extinctions

According to Xiao, there are five known mass extinctions in animal history, the “Big Five”, which include the Ordovician–Silurian extinction (440 million years ago), the Late Devonian extinction (370 million years ago), the Permian–Triassic extinction (40 million years ago), and the Permian–Triassic extinction. Extinction (250 million years ago), Triassic–Jurassic extinction (200 million years ago), and Cretaceous–Paleogene extinction (65 million years ago).

“Mass extinctions are recognized as important steps in the evolutionary trajectory of life on this planet,” Evans and his team wrote in the study. Whatever the cause of the mass extinction, the result was a number of major changes in environmental conditions.

“In particular, we find support for a decrease in global oxygen availability as the mechanism responsible for this extinction. This suggests that the diversity pattern of abiotic controls throughout the more than 570 million-year history of animals on this planet.” significant impact,” the authors wrote.

Fossil tracks in the rock tell researchers what the creatures that died in this extinction event would have looked like. And they looked, in Evans’ words, “strange.”

“These organisms occur so early in the evolutionary history of animals that in many cases they seem to be experimenting with different ways of building large, sometimes mobile, multicellular bodies,” Evans said. “There are many ways to recreate what they looked like, but the takeaway is that before this extinction, the fossils we find don’t fit well into the ways animals are classified today. Essentially Since then, this extinction may have helped pave the way for the evolution of animals as we know them.”

This article was originally published on The HuffPost and has been updated.

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World Nation News Desk
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