Posted by TARA THEAN Friday, November 25, 2011 at 5:00 am
22 Comments • Related Topics: climate science, disasters, oceans , dinosaurs, endangered, extinction, paleontology, wildlife
Earth history is different from ordinary history: it's much harder to nail down specific dates when everything happened millions of years ago and over huge, slow timescales. But it can be done, as shown by paleontologists who have pinpointed the exact date of the largest mass extinction to ever occur on earth. The end-Permian mass extinction, which their study calls the “most severe biodiversity crisis in earth history,” wiped out 95% of marine life and 70% of life on land about 252.28 million years ago.
This huge exodus of creatures from the planet happened pretty quickly, according to the study published last week in Science. It lasted less than 200,000 years, and some species may even have met their end within 20,000 years.
That sounds like a long time, but it's a blink of an eye in geological years. “That's probably one of the more surprising things – that we're getting an impression that this event happened very quickly,” University of Calgary geosciences professor Charles Henderson said. Henderson's team figured out the specific timing of the extinction by examining crystals found in volcanic ash beds in South China in combination with 1,500 fossil species found in rock layers.
A major finding of the study was also that marine and land organisms disappeared from the earth at around the same time, which has been an ongoing debate among scientists. The crisis obliterated insects, forests, amphibians, reptiles, and mammal ancestors – probably the closest we've come to having life completely wiped off the face of the earth. All of this happened during the end-Permian, when a chunk of land called Pangea existed in place of the continents we know today. Recovering from this apocalypse started with reptile-like creatures: critters such as the pig-sized, horny-beaked Lystosaurus crept in first, and others – including the dinosaurs – found their place later on.
Read more:
http://ecocentric.blogs.time.com/2011/11/25/life-in-the-time-of-the-great-dying/