A new study conducted by Virginia Tech geobiologists suggests that the cause of the first known mass extinction of animals was decreased global oxygen availability, leading to the loss of a majority of animals present near the end of the Ediacaran Period roughly 550 million years ago.
The study led by Scott Evans shows the earliest mass extinction of about 80 percent of animals across this interval.
Scientists still don’t know what caused the drop in global oxygen. “The short answer to how this happened is we don’t really know,” Evans said. “It could be any number and combination of volcanic eruptions, tectonic plate motion, an asteroid impact, etc., but what we see is that the animals that go extinct seem to be responding to decreased global oxygen availability.”
In another study, Virginia Tech scientists found that anoxia, the loss of oxygen availability, is affecting the world’s fresh waters. This is the result of the warming of waters brought on by climate change and excess pollutant runoff from land use. Warming waters reduces freshwater’s capacity to hold oxygen, while the breakdown of nutrients in runoff by freshwater microbes consumes oxygen.
“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,” explained Evans.
www.scitechdaily.com/550-million-years-ago-researchers-shine-new-light-on-earths-first-known-mass-extinction-event/