(ORDO NEWS) — Scientists continue to argue about the causes of extinction at the end of the Paleozoic era – the most massive in the history of the Earth.
According to new data, it lasted much longer than is commonly believed, and was accompanied by a long gradual warming.
During its history, the Earth’s biosphere has experienced several dramatic episodes, when many species perished at once in very short (by geological standards) periods of time.
Mass extinctions were accompanied by a change in geological periods or even eras, and each time meant a turn in the development of life.
The most grandiose was the extinction of species at the end of the long Paleozoic era, which put an end to the dominance of plate-skinned fish, huge cephalopods, as well as trilobites and other outlandish arthropods.
There were times when various reptiles and seed plants dominated, between which the first small mammals, our ancestors, timidly ran.
What happened then, about 252 million years ago? Why did 73% of terrestrial vertebrate species and more than 95% of marine inhabitants disappear? Paleontologists continue to argue about this.
Most often, they mention global climate change, namely, warming, associated, among other things, with the eruption of huge Siberian traps volcanoes.
Now on this place, among other things, the Putorana plateau formed by them is spread.
Previously, scientists suggested that the Permian extinction happened very quickly – in just 40 thousand years, which is extremely short in terms of geology.
During this time, the average temperature on our planet allegedly rose by 10 degrees, and the pH of the water in the ocean dropped sharply.
According to a number of experts, something similar is happening on Earth now.
However, the authors of a new article in the journal Paleontology have doubts about this.
They argue that such a model is contradicted by the data of geochemistry and paleontology, indicating significant changes in conditions on Earth before the onset of the most dramatic stage of extinction.
The scientists used fossils of a number of barnacles (Ostracoda), small arthropods that live in shells (including those formed by calcium carbonate) and lead a planktonic lifestyle.
Their remains were found on the territory of Iran and belong to the Changxing stage – that is, to the very end of the Paleozoic.
Using a complex physical technique called secondary ion mass spectrometry , the researchers estimated the ratio of individual oxygen and carbon isotopes in the barnacle skeleton and calculated the ambient temperature based on this.
It turned out that the temperature of the water in which the ancient crustaceans swam began to increase long before the extinction itself – about 300 thousand years earlier.
During this time, gradual global warming led to an increase in average temperature by 12 degrees, which eventually caused the collapse of most ecosystems – especially marine ones.
The novelty of this study lies in the significant expansion of the time frame of the grandiose extinction.
It helps to better understand which of the factors served as a “trigger” of destructive changes that continued with the acidification of the oceans, the lack of oxygen in them and the change of geological eras.
Contact us: [email protected]