December 22, 2010

Fossil Site Offers Clues To Mass Extinction Recovery

A massive new fossil site discovered in southwestern China marks the first discovery of a complete ecosystem which recovered following a mass extinction.

According to Guardian Science Correspondent Ian Sample, "the spectacular haul of 20,000 fossils," which was discovered at a hillside in what it now Luoping county in the Yunnan Province of China, were "beautifully preserved" and included "mollusks, sea urchins and arthropods, alongside much larger animals that occupied the top of the food chain, such as carnivorous fish and the first ichthyosaurs, predatory marine reptiles that grew to four meters long."

The work, which was led by scientists from the Chengdu Geological Center in China, is the subject of a paper co-written by Bristol University School of Earth Sciences Professor Mike Benton and published this week in the Proceedings of the Royal Society B.

In a press release, officials from the university said that the site's discovery "has filled in a sizeable gap in our understanding of how life on this planet recovered from the greatest mass extinction of all time." That extinction, which occurred roughly 250 million years ago during the Permian Period, saw a sustained period of high volcanic activity and rising temperature wipe out nearly all life on the planet.

According to Sample, the cataclysmic event "was unequaled in scale" and resulted in the demise of some 96% of marine life and 70% of land-based vertebrates.

"Only one in ten species survived, and these formed the basis for the recovery of life in the subsequent time period, called the Triassic," the Bristol University press release added. "The new fossil site"¦ provides a new window on that recovery, and indicates that it took about 10 million years for a fully-functioning ecosystem to develop."

Furthermore, Benton notes that the recovered ecosystem included "much greater diversity" than was discovered during the Early Triassic period. The number of different species discovered at the site was "close to pre-extinction levels," he said.

According to the press release, that includes the "debut" of predators "such as the long-snouted bony fish Saurichthys, the ichthyosaur Mixosaurus, the sauropterygian Nothosaurus and the prolacertiform Dinocephalosaurus."

"The fossils at Luoping have told us a lot about the recovery and development of marine ecosystems after the end-Permian mass extinction," Benton added in a statement. "There's still more to be discovered there, and we hope to get an even better picture of how life reasserted itself after the most catastrophic global event in the history of our planet."


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