Olson's Extinction: The Permian's Dirty Little Secret Die-off

In one of Charles R. Knight's famous 19th century paintings, an Early Permian dimetrodon (don't call it a dinosaur!) seems to be enjoying itself, happy and carefree, with no idea about the mass extinctions on the horizon. (Credit American Museum of Natural History/Wikimedia Commons) It's the mass extinction you probably haven't heard about, because for a long time researchers have questioned whether it even existed. But a growing body of evidence, including a study published today, has strengthened the case for Olson's Extinction — which played a role in our species eventually dominating the planet, for better or worse (mostly worse). For whatever reason, people seem to dig mass extinctions. At least the ones in the past. Far fewer folk are entertained by (or even aware of) what many researchers are calling the sixth mass extinction, going on right now and all thanks to our own meddling species. But I digress. The fossil record provides ample evidence for five big mass extinctions, most infamously the Great Dying at the end of the Permian (or end-Permian, if you want to be a cool paleo-nerd). That was when, about 250 million years ago, some 90 percent of marine species and more than 70 percent of land species shuffled, swam or slithered off this mortal coil. (For many people, what springs to mind when they hear the term "mass extinction" is likely the end-Cretaceous event of 66 million years ago, when a number of species, including all the dinosaurs that weren't birds, went buh-bye. But for sheer biodiversity-crushing scale, the end-Permian wins the deathrace, hands down.)