Life was nearly wiped out 250 million years ago, with only 10 percent of plants and animals surviving. It is currently much debatedhow life recovered from this cataclysm, whether quickly or slowly. Recent evidence for a rapid bounce-back is evaluated in a newreview article by Dr Zhong-Qiang Chen, from the China University ofGeosciences in Wuhan, and Professor Michael Benton from theUniversity of Bristol. They find that recovery from the crisislasted some 10 million years, as explained May 27 in Nature Geoscience. There were apparently two reasons for the delay, the sheerintensity of the crisis, and continuing grim conditions on Earthafter the first wave of extinction. |
The end-Permian crisis, by far the most dramatic biological crisisto affect life on Earth, was triggered by a number of physicalenvironmental shocks -- global warming, acid rain, oceanacidification and ocean anoxia. These were enough to kill off 90per cent of living things on land and in the sea. Dr Chen said: "It is hard to imagine how so much of life couldhave been killed, but there is no doubt from some of the fantasticrock sections in China and elsewhere round the world that this wasthe biggest crisis ever faced by life." Current research shows that the grim conditions continued in burstsfor some five to six million years after the initial crisis, withrepeated carbon and oxygen crises, warming and other ill effects. Some groups of animals on the sea and land did recover quickly andbegan to rebuild their ecosystems, but they suffered furthersetbacks.
Life had not really recovered in these early phasesbecause permanent ecosystems were not established. Professor Benton, Professor of Vertebrate Palaeontology at theUniversity of Bristol, said: "Life seemed to be getting backto normal when another crisis hit and set it back again. The carboncrises were repeated many times, and then finally conditions becamenormal again after five million years or so." Finally, after the environmental crises ceased to be so severe,more complex ecosystems emerged. In the sea, new groups, such asancestral crabs and lobsters, as well as the first marine reptiles,came on the scene, and they formed the basis of future modern-styleecosystems. Professor Benton added: "We often see mass extinctions asentirely negative but in this most devastating case, life didrecover, after many millions of years, and new groups emerged.
Theevent had re-set evolution. However, the causes of the killing --global warming, acid rain, ocean acidification -- sound eerilyfamiliar to us today. Perhaps we can learn something from theseancient events.".
We are high quality suppliers, our products such as China Open Frame LCD Monitor , Industrial Motherboards for oversee buyer. To know more, please visits Touch Screen Industrial Panel PC.
Related Articles -
China Open Frame LCD Monitor, Industrial Motherboards,