First Mass Extinction Likely Caused by 'Utterly Weird' Animals
Animals shaped like 'Frisbees and lumpy mattresses' may have killed early Ediacarans
By Jenn Gidman,  Newser Staff
Posted Aug 1, 2016 1:01 PM CDT
The disc-like fossils shown here are the preserved remains of holdfast structures used by the Ediacaran species Aspidella that went extinct about a million years after these individuals died and were...   (Simon Darroch, Vanderbilt University)

(Newser) – New fossil evidence dug up in Namibia lends credence to the theory that we should blame "ecosystem engineers" for the world's first mass extinction, and that's not a euphemism for man, asteroids, or aliens. Instead, per a Vanderbilt University study published in the October issue of the Palaeogeography, Palaeoclimatology, and Palaeoecology journal, the end of the era of Ediacara biota (early multi-celled, soft-shelled creatures) brought about 540 million years ago was likely to blame on the metazoans, the earliest animals that started to proliferate during a "short" 30-million-year stage known as the Cambrian explosion. The Washington Post describes these early animals as "utterly weird" creatures that were often "little more than pipes or fleshy bags glued to the seafloor" (some scientists have compared them to "Frisbees or even lumpy mattresses") and that often didn't move, much like sea coral today. But they may have wreaked enough ancient havoc to cause major damage to the Ediacarans, possibly wiping them out completely.

"These new species … changed the environment in ways that made it more and more difficult for the Ediacarans to survive," study lead author Simon Darroch says in a release. Darroch and his team say they found a well-kept group of fossils of both Ediacarans and metazoans, suggesting an "ecological association" between the two, though it apparently wasn't one that ended well for the Ediacarans: In a 2015 study, Darroch's team found evidence of "stressed-looking" Ediacarans near animal burrows, with evidence of "the last of the Ediacara biota clinging on for grim death." The Ediacarans are long gone, but Darroch warns history has the potential to repeat itself. "There is a powerful analogy between the Earth's first mass extinction and what is happening today," he says. "The end-Ediacaran extinction shows that the evolution of new behaviors can fundamentally change the entire planet, and today we humans are the most powerful 'ecosystems engineers' ever known." (To wit: Our own extinction may be next.)