1·During the Ordovician, most life was in the sea, so it was sea creatures such as trilobites, brachiopods and graptolites that were drastically reduced in number.
在奥陶纪，大多数生命都生活在海洋里，所以海洋生物，例如三叶虫、腕足类动物与笔石动物的数量在此时急剧减少。