英语资讯
News

科学美国人60秒:Biggest Mass Extinction Was Fastest, Too

Source: scientificamerican    2014-02-25  我要投稿   论坛   Favorite  

It was the largest of the five major mass extinctions in Earth’s history—well before the dinosaur-killer 66 million years ago. What’s called the End Permian extinction, 252 million years ago, wiped out 96 percent of aquatic species and 70 percent of species on land. Scientists have been trying to gauge the time frame of the extinction, in the hopes of determining its causes.

Now researchers say it’s the fastest mass extinction known.

Using new tools and models—including a fresh analysis of rock formations in China—the researchers determined that the extinction took only about 60,000 years. That’s incredibly quick by geological standards, and is more than 10 times faster than previous estimates.

The report is in the Proceedings of the National Academy of Sciences. [Seth D. Burgess, Samuel Bowring and Shu-zhong Shen, High-precision timeline for Earth’s most severe extinction] 

study author Samuel Bowring from M.I.T. says they can’t yet compare the speed of the previous extinction to the extinction rates caused by human activities today. But, he says, their research is starting to help reveal how past environmental changes that influenced extinctions—such as levels of carbon dioxide in the atmosphere—compare to the changes in those levels seen today. In the midst of what many call the sixth extinction.

—Cynthia Graber


 


将本页收藏到:
上一篇:科学美国人60秒:Biggest Mass Extinction Was Fastest Too
下一篇:科学美国人60秒:Young Musicians Reap Long-Term Neuro Benefits

最新更新
论坛精彩内容
网站地图 - 学习交流 - 恒星英语论坛 - 关于我们 - 广告服务 - 帮助中心 - 联系我们
Copyright ©2006-2007 www.Hxen.com All Rights Reserved