The timing of the largest extinction in the history of the Earth
The largest mass extinction in the history of the Earth is the Permian, which happened 252 million years ago. It completely changed the living world of our planet and “opened” the way for dinosaurs, according to PNAS .
Scientists are still investigating the reasons for this event and establishing why some species became extinct, while others survived. Extinction has been uneven, new research has shown, with rapid progress in seas and oceans and slower extinction on land.
Fossils are better preserved underwater, according to paleontologists. They sink to the bottom, are covered with precipitation and turn to stone. Thanks to them, it became known that 252 million years ago, more than 85% of species living in water became extinct, and this happened within 100 thousand years. From a geological point of view, this is very fast.
To better understand what was happening on land during this time, the authors of the new study examined the fossils of 588 four-legged fossils that lived in the territory of modern South Africa in the Karoo River basin. Then they grouped the remains by age – this helped to understand in what time period certain species existed and when they disappeared.
“Ultimately, this allows us to quantify how much extinction is occurring and how quickly new species are emerging,” the authors explained.
One of the species found by scientists is Lystrosaurus, an early herbivorous relative of mammals. According to the study, while other animals were dying out, he felt quite comfortable. Scientists suggested that the environment changed gradually, and the Lystrosaurs managed to adapt to it, while other individuals did not.
Analysis of the remains showed that the extinction on land took much longer than in the oceans. If the history of the Earth were compressed into one year, then the marine extinction would take 14 minutes, and the terrestrial extinction ten times more, two hours and twenty minutes.
The reasons for this discrepancy are not yet very clear. Climate change on the planet was gradual and had a “cumulative” effect – ecosystems were slowly destroyed until they passed a certain point of no return.
“Today, Keans can absorb a lot of carbon dioxide or raise temperatures without the knowledge of people, and then all of a sudden you get sudden ecosystem disruptions such as ocean acidification and coral bleaching. Perhaps something similar happened then, too, ”noted the authors of the scientific work.
Scientists have previously investigated the Triassic extinction. According to them, it was associated with a rainstorm that lasted for millions of years.