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有人提出物种的集群绝灭是地外因素所造成的,可能是某些大陨星和慧星(火球陨石)撞击地球所引起的.陨石撞击的主要证据是,白垩-第三系界线是动物群的一个大变更时期.界线粘土中富集铂族金属元素,尤其是铱.这些元素在宇宙中较为丰富;相比之下,在地壳中的含量则十分稀少.它们大量富集于白垩-第三系界线上.因此有人认为它们主要来源于地球之外.然而,对于与集群绝灭事件一致的地外物体撞击证据
It was suggested that the extinction of species in the cluster was caused by extra-terrestrial factors, possibly caused by the impact of some large meteorites and comet (fireball meteorites) on the Earth.The main evidence of the impact of meteorites is that the chalk-Tertiary boundary is a fauna Of the period of a large change in the clay boundary line is enriched in platinum group metal elements, especially iridium.These elements in the universe is more abundant; In contrast, the content in the crust is very rare.A large number of them are enriched in the chalk - Three lines, so some people think they mainly come from outside the earth.However, for extinction consistent with extinction cluster object evidence of impact