The Annihilation Was Not Just In the Seas

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.

"When you talk about diversity loss and recovery, it's not something that rebounds in ten years. It takes millions of years," said Jessica Whiteside, a paleobiologist at Brown University. "This is basically a warning call about the loss of biodiversity. It's something that takes a substantial amount of time to rebound from."

In a study published last year in the journal Geology, Whiteside found that it took as many as 10 million years for marine species to recover from the Permian-Triassic extinction. To find out what was happening on land during the same period, she and colleague Randall Irmis analyzed close to 8,600 fossils from South Africa and Russia.

When they counted types and numbers of creatures that existed before and after the extinction, they found that nearly 78 percent of terrestrial species disappeared as the Permian period ended. Among the few creatures that remained, they reported in Proceedings of the Royal Society B, was a German-Shepard sized mammal-like animal called Lystrosaurus and a lizard-like creature called Procolophon.

The species that remained faced major challenges. For eight million years after the extinction event was over, researchers found that there was instability in the ratio of carbon atoms on Earth. That suggests that predator-prey relationships were totally out of whack.

In a healthy ecosystem, the food web looks like a pyramid, with lots of creatures on the bottom rungs being eaten by successively fewer species as you work your way up to the top predators. But after the Permian period ended, there were often just one or two species filling niches that were once occupied by 20 or 30 kinds of animals.

Read more at Discovery News