November 30, 2022

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The first mass extinction occurred, about 550 million years ago, due to a lack of oxygen

The first mass extinction occurred, about 550 million years ago, due to a lack of oxygen

A new study by geoscientists at Virginia Tech’s College of Science indicates that the first mass extinction of species occurred about 550 million years ago. Scott Evans, who led the research, stated that this extinction led to the extinction of 80 percent of the world’s population. Species that lived on Earth during the Ediacaran period. This included the loss of many different species of animals, but those that particularly depended on large amounts of oxygen were the hardest hit. Evans said this indicates that the environment was controlling the extinction, like all other mass extinctions in history.

The results and description of the research have been published in the Proceedings of the National Academy of Sciences (DOI: 10.1073/pnas.2207475119).

“Environmental changes, such as global warming and decreased oxygen availability, can lead to mass extinction of animals and profound disruption and reorganization of ecosystems,” said Shuhai Xiao of the Department of Earth Sciences at Virginia Tech College of Science. “This has been proven many times in the study of Earth’s history, including work on the first extinctions documented in the fossil record. This study therefore tells us about the long-term impact of current environmental changes on the biosphere.

What exactly caused oxygen levels to drop half a billion years ago? This is still a topic of debate. “The short answer to how this happened is we really don’t know,” Evans said. “It could be massive volcanic eruptions, tectonic plate movements, an asteroid collision, or a combination of these. But we see that animals that have gone extinct seemed to respond to reduced oxygen availability globally.”

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Evans and Xiao’s study is more relevant than you think. In another study, Virginia Tech scientists found that reduced oxygen availability affects aquatic ecosystems. reason? Rising water temperatures caused by climate change and excessive runoff of pollutants from land uses. Water warming reduces the ability of freshwater to hold oxygen, while nutrient decomposition by freshwater microbes results in oxygen consumption.

“Our study shows that, as with all other mass extinctions in Earth’s past, this first mass extinction of newly discovered animals was caused by significant climate change. This is yet another in a long list of warnings that show the dangers of the current climate crisis,” Evans said.

The Ediacaran lasted about 94 million years – from about 635 to 541 million years ago. It was preceded by the cooler and followed by the Cambrian period. There are five mass extinctions of species: the Ordovician Extinction – which occurred about 438 million years ago, the Devonian Extinction – about 374 million years ago, the Permian Extinction – about 250 million years ago, the Triassic Extinction – about 201 million years ago, and the Cretaceous Extinction which occurred before About 66 million years ago.

“The mass extinctions were recognized as important steps in the evolutionary trajectory of life on this planet,” Evans and his team wrote in the paper. Whatever the cause of the mass extinction, the result was several major changes in environmental conditions. In particular, we find support for reduced global oxygen availability as a mechanism responsible for this extinction. This suggests that abiotic control had a significant impact on patterns of diversity over the hundreds of millions of years of Earth’s animal history, the paper’s authors said.

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Fossils from this period tell us what the creatures that died in this extinction looked like. According to Evans, they looked “weird”. “These organisms appear so early in the evolutionary history of animals that in many cases they seem to be experimenting with different ways of building large, mobile, sometimes multicellular bodies,” Evans said. “There are many ways to reconstruct their appearance, but the most important thing is that fossils found before this extinction often do not match the ways we classify animals today. This extinction may have helped pave the way for the evolution of animals as we know them,” he noted.