许多科学家都认为,在生物演化史上的6500万年前,有过一次巨大的灾难,导致了恐龙的灭绝。这次灾难被认为是一个巨大的天外来客撞击了墨西哥湾,形成了一个深似美国科罗拉多大峡谷的巨坑,而且又使数十亿吨的碎岩石溅到大气中或被气化。这一时期正处于白垩纪初期和三叠纪晚期交替的阶段,学术上称为K-T时期。 Many scientists believe that in the history of biological evolution 65 million years ago, there was a huge disaster that led to the extinction of dinosaurs. The catastrophe was considered to be a huge extraterrestrial guest who struck the Gulf of Mexico, forming a deep hole that resembled the Grand Canyon of the United States, and caused billions of tons of broken rocks to be splashed into the atmosphere or gasified. This period is in the early stage of the Cretaceous and the later transition of the Triassic period, which is academically called the K-T period.