Life Itself Caused the First Mass Extinction

mass extinction
© CG Kenchington

In a paper published in Proceedings of the Royal Society B, paleontologists claim that the first mass extinction of animals on Earth happened around 540 million years ago, during the Ediacaran Period, and it was caused by the fast paced evolution of life itself, and not from some cosmic or natural cataclysms.

“There are strong parallels between the first mass extinction and modern days. The extinction at the end of the Ediacaran Period shows that the occurrence of new behavior among animals could completely change the whole appearance of our planet, and in turn destroy our ecosystems. We, as people seem to be the most powerful ecosystem engineers in all of history”, explains Simon Darroch from the Vanderbilt University in Nashville, USA.

Darroch and his colleagues came to this unexpected conclusion after studying the species composition and structure of the last multicellular Ediacaran organisms that lived 545 million years ago. Remains of the organisms were recently discovered in Namibia.

Scientists explain that many strange multicellular animals appeared on our planet around 600 million years ago and they disappeared without a trace a little before the Cambrian explosion – the era of massive expansion of animal diversity and the appearance of all groups of modern-day life.

Darroch explains that a distinctive characteristic of those early organisms is that they were able to use oxygen (a gas that was toxic for most microbes) as an energy source. Despite their stationary way of life, this allowed them to quickly spread across the primordial ocean and invade every corner of the Earth relatively quickly.

Why did these creatures disappear? Analysis of the remains discovered in Namibia show that their “successors” were the reason – the representatives of the Cambrian fauna, which literally transformed the ocean underneath them, making it unsuitable for Ediacaran creatures.

The main difference between the Cambrian fauna and its Ediacaran competition was that a large part of its representatives were mobile and were able to move from one place to another, which allowed them to actively search for food. This ability helped them to overturn their Ediacaran “predecessors” and take their place among ecosystems.

According to Darroch, this is backed up by the fact that the diversity of Ediacaran animals in the Namibian alluvial was very low in comparison with earlier deposits of their remains, even though, according to the chemical make-up of surrounding rocks, they had no trouble accessing oxygen and food.

Such processes of one species overturning another and taking its place has always happened in nature, but back then, this changeover happened so quickly, that, from a geological point of view, it is very similar to a typical mass extinction caused by some planetary cataclysm.

So, it is possible that mass extinctions could be caused not only by hot magma, ecological catastrophes or falling asteroids, but by the appearance of new life forms and their evolution as well.

Scientists conclude that such a discovery appears as a glaring example of the future that our planet could hold one day.