the first mass extinction is not what we thought

It is a discovery scientific that can change a lot of things: according to a new examinationwould there be a sixth mass extinction on the earth, which would have taken place before all the others. We explain to you.

A sixth mass extinction hitherto forgotten

Everyone knows that the influence of human activity is harmful to our planet. If the question is discussed, many scientists warn us and consider it we would have triggered a new cycle of mass extinction. This term is used to denote a biological and/or ecological crisis which, within a few million years, causes at least 75% of the plant and animal species to disappear from the surface of the Earth and the oceans.

Today it is generally accepted that Earth has experienced five mass extinctions in its history. The latest, everyone has already heard about it: it took place about 65 million years ago, and it is the one that is largely responsible for the disappearance of the dinosaurs. As for the first one, it would be due to a great ice age and would date back to 445 million years ago. At least we thought so until today.

Indeed, a recent study conducted by postdoctoral researcher Scott Evans, a professor at Virginia Tech (or “Virginia Polytechnic Institute and State University”), has made it possible to reach the conclusion that the first major extinction would actually date from 550 million years ago, at the end of the Ediacaran era.

A planet lacking oxygen

The Ediacaran is a period in which many species evolved: it is from this period that we date the oldest traces of multicellular life. Only more than 80% of them have disappeared, without knowing exactly why. For many scientists, this brutal phenomenon is due to the emergence of species that have greatly disrupted the food chain. But the study we’re talking about today goes in the opposite direction and says soit is actually the first mass extinction on Earth.

This would be caused by a sudden drop in the level of oxygen on our planet. In any case, this is what the study results suggest: out of 70 studied species that existed 550 million years ago, only 14 still populated the Earth 10 million years later. Scientists have not found drastic differences in diet between surviving and extinct species and do not consider environmental changes to have been sufficient to cause some fossils to disappear. For them, the cause is therefore necessarily due to a profound environmental change.

And what put them on the trail of lower oxygen levels was the fact that all the fossils found belong to animals with roughly similar organisms, often quite massive, that are more likely to adapt to lower oxygen levels. However, scientists have not been able to define the reason for this sudden disappearance. a large part of the oxygen (volcanic eruption? Meteorite?…). Nevertheless, they figured it out this event would be the origin of much of the life we ​​know todaysince it was after this mass extinction that species similar to those living on Earth today appeared.

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