The work shows a significant loss of diversity during the Ediacaran period, which lasted from 635 million to 540 million years ago

A new study by geologists at Virginia Tech has traced the cause of the first known mass extinction of animals to a decrease in the global availability of oxygen, resulting in the loss of the majority of existing animals at the end of the period. Ediacaran about 550 million years ago.

Research led by Scott Evans, a postdoctoral researcher in the Department of Earth Sciences, part of Virginia Tech College of Science, shows this first mass extinction of about 80% of animals during this period. “This included the loss of many different species of animals, but it appears that those whose body plans and behaviors indicate that they depend on large amounts of oxygen have been particularly affected,” Evans said. “This indicates that the extinction event was ecologically controlled, like all other mass extinctions in the geological record.”

Evans’ work was published on November 7 in Proceedings of the National Academy of Sciences, a peer-reviewed journal of the National Academy of Sciences. The study was co-authored by Shuhai Xiao, who is also a professor in the Department of Earth Sciences, and several researchers led by Mary Drosser of the Department of Earth and Planetary Sciences at the University of California, Riverside, where Evans holds her master’s and doctoral degrees.

“Environmental changes, such as global warming and deoxygenation events, can lead to mass animal extinctions and profound ecosystem disruption and reorganization,” said Xiao, an associate member of the Center for Global Change, part of Virginia Tech Fralin Life. Science Institute. This has been demonstrated repeatedly in the study of Earth’s history, including this work on the first extinction documented in the fossil record. Thus, this study informs us of the long-term impact of current environmental changes on the biosphere. »

See also  Spotify, a lazy king with Apple platforms

What exactly caused the global oxygen decline? It is still under discussion. “The short answer for how this happens is we don’t really know,” Evans said. “It could be any number and combination of volcanic eruptions, tectonic plate movements, asteroid impact, etc., but what we see is that animals that are disappearing seem to respond to a decrease in global oxygen availability.”

Evans and Xiao’s study was more timely than one might imagine. In an independent study, Virginia Tech scientists recently found that hypoxia, the loss of oxygen availability, is affecting the world’s freshwater. the reason? Water warming caused by climate change and excessive runoff of pollutants from land uses. Warming of water reduces the ability of fresh water to hold oxygen, while degradation of nutrients in runoff by freshwater microbes leads to oxygen uptake.

“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 significant climate change — another change in a long list of cautionary tales that illustrate the dangers of the current climate crisis for animals,” he said. Evans, a fellow in geobiology at the Agoron Institute.

A little perspective: The Ediacaran period spanned about 96 million years, and ended on both sides with the end of the Cryogenic period – 635 million years ago – and the beginning of the Cambrian period – 539 million years ago. Extinction occurs before a major break in the geologic record, from the Proterozoic to the primordial eon.

There are five known mass extinctions in animal history, the “Big Five,” according to Xiao, including the Ordovician-Silurian Extinction (440 million years ago), the Late Devonian Extinction (370 million years ago), and the Permian-Triassic extinction (250 million years ago). ), the Triassic-Jurassic extinction (200 million years ago) and the Cretaceous and Paleogene extinction (65 million years ago).

See also  Error affecting wireless charging of some pixels

“It is well known that mass extinctions are milestones in the evolutionary path of life on this planet,” Evans and his team wrote in the study. Whatever the reason for the mass extinction, the result has been multiple major changes in environmental conditions. “In particular, we find support for declining global oxygen availability as the mechanism responsible for this extinction. This indicates that abiotic controls have had significant effects on patterns of diversity throughout the more than 570 million years of animal history on the planet,” the authors wrote. .

Fossil footprints in the rock tell researchers what creatures that died during this extinction event would have looked like. And they looked, in the words of Evans, “weird.”

“These organisms occur so early in the evolutionary history of animals that in many cases they seem to be testing different ways of building large, multicellular and sometimes mobile bodies,” Evans said. “There are many ways to recreate their appearance, but the bottom line is that prior to this extinction, the fossils that we find do not always match up perfectly with the way we classify animals today. Essentially, this extinction may have helped pave the way for the evolution of animals as we know them. . »

The study, like dozens of other recent publications, emerged from the COVID-19 pandemic. Since Evans, Xiao and their team had no access to the field, they decided to build a global database based primarily on published records to test ideas about the evolution of diversity. “Others suggested there might have been an extinction at the time, but there was a lot of speculation. So we decided to put together everything we could to try and test these ideas,” Evans said. Much of the data used in the study was collected by Druser and several graduate students. At the University of California Riverside.

See also  Teenage Mutant Ninja Turtles: Shredder's Revenge - Over 1 million units sold in 1 week

Leave a Reply

Your email address will not be published.