作为地球史上消亡物种排行第三的大灭绝，奥陶系-志留纪大灭绝有两个死亡高峰期，其中相隔数十万年时间。
The third largest extinction in Earth's history, the Ordovician-Silurian mass extinction had two peak dying times separated by hundreds of thousands of years.
五次大灭绝中发生最早的一次是奥陶纪末期或者奥陶纪-志留纪大灭绝事件，发生在大约4亿4千4百万年前。 许多科学家估计这次规模是五次当中第二大的。
The earliest of the Big Five, the end-Ordovician or Ordovician-Silurian extinction events some 444 million years ago, are reckoned by many to be the second largest.
阿尔拜虫目放射虫最早的代表出现于志留纪，从晚泥盆世开始繁盛，于二叠纪末期灭绝，是晚古生代特有的放射虫类群。
Representative elements of order Albaillellaria firstly appear in Silurian, which prosperous in Late Devonian, and extinction in end-Permian, is the characteristic group of Late Paleozoic Radiolaria.
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