About 252 million years ago, Earth experienced its most devastating extinction in the history of life on our planet. And while scientists have long known that more than 80 percent of ocean-dwelling species disappeared, they have long debated what happened on land.

Now, researchers are reporting that land-dwelling species were equally decimated during the extinction, which ended an era called the Permian period. After the massive wave of devastation swept through, just a few "disaster" species remained, including a handful of large four-legged creatures, a new study found.

Recovery, the study also found, was slow. Animals that survived the near-apocalypse remained on the edge of collapse for the next eight million years, before the food supply stabilized again.

As we enter what appears to be the Earth’s sixth major extinction event, the new findings emphasize the value of having a wide range of creatures around, and more warnings of the danger of letting too many species disappear....