显生宙以来,发生过六次全球性的动物集群绝灭mass extinction)事件,其时间为寒武纪末、奥陶纪末、泥盆纪弗拉斯期(Frasnian)末、二叠纪末、三叠纪末和白垩纪末。这些在相当短暂的地质时期许多门类动物突然绝灭的原因难于用生存竞争或其他均变论的观 Six global mass extinction events occurred during the Phanerozoic since the end of the Cambrian, Late Ordovician, Devonian Frasnian, and Late Permian Triassic and Late Cretaceous. The reasons for the abrupt extinction of many species in relatively short geologic times are difficult to justify by either competition for survival or other permutations