Geobiologists from the United States have shed new light on the first known mass extinction event on Earth, which occurred 550 million years ago during a period known as the Ediacaran, according to the details of a new study published by ScienceAlert. The study was conducted by the Virginia Tech College of Science and spearheaded by Scott Evans, a postdoctoral researcher in the Department of Geosciences. The study reveals the earliest mass extinctions of approximately 80% of animals during this time period.
"This included the loss of many different types of animals, however, those whose body plans and behaviours indicate that they relied on significant amounts of oxygen seem to have been hit particularly hard," Mr Evans said. "This suggests that the extinction event was environmentally controlled, as are all other mass extinctions in the geologic record."
According to Virginia Tech, Mr Evans' work was published on November 7 in the 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, also a professor in the Department of Geosciences, and several researchers led by Mary Droser from the University of California, Riverside's Department of Earth and Planetary Sciences, where Mr Evans earned his master's degree and PhD.
"Environmental changes, such as global warming and deoxygenation events, can lead to massive extinctions of animals and profound disruption and reorganisation of the ecosystem," said Shuhai Xiao, who is an affiliated member of the Global Change Centre, a part of the Virginia Tech Fralin Life Sciences Institute. "This has been demonstrated repeatedly in the study of Earth history, including this work on the first extinction documented in the fossil record. This study thus informs us about the long-term impact of current environmental changes on the biosphere."
There are five known mass extinctions that stand out in the history of animals, the “Big Five,” according to Xiao, including the Ordovician-Silurian Extinction (440 million years ago), the late Devonian Extinction (370 million years ago), the Permian-Triassic Extinction (250 million years ago), the Triassic-Jurassic Extinction (200 million years ago), and the Cretaceous-Paleogene Extinction (65 million years ago), the Virginia Tech College of Science said in the release.
Mr Evans and his colleagues compiled data on rare fossils of the squishier kinds of animals from around the world that date to the Ediacaran. They found that sudden shifts in biodiversity that had previously been detected weren't the result of mere sampling biases.
"Our study shows that, as with all other mass extinctions in Earth's past, this new, first mass extinction of animals was caused by major climate change another in a long list of cautionary tales demonstrating the dangers of our current climate crisis for animal life," said Evans.