许多早期哺乳动物在强大的恐龙面前曾经只是一个个卑微的可怜虫,为了避免成为恐龙的美味大餐,它们不得不缩成一个个毛毛球,瑟瑟发抖地躲在阴暗的角落中,而且这一情形持续长达1.5亿年之多。但随着6500万年前恐龙从地球上灭绝,这些哺乳动物的祖先似乎找到了生存的自信。英国伦敦大学学院古生物学家对白垩纪早期哺乳动物的化石与后来的哺乳动物化石进行了分析,并对比了哺乳动物进化前后的变化发现,在白垩纪晚期小行星撞击事件引发地球物种大灭绝之前,地球上胎盘哺乳动物的进 Many early mammals used to be just humble parrots in the face of powerful dinosaurs, and in order to avoid becoming dinosaurs, they had to shrink into pompons and shuddered in shadowy corners, and this The situation lasted as long as 150 million years. But with the extinction of dinosaurs 65 million years ago from Earth, the ancestors of these mammals seem to have found the confidence to survive. Palaeontologists at the University College London in the UK analyzed the Cretaceous mammalian fossils and later mammalian fossils and compared mammalian evolution before and after evolution. Before the end of the Cretaceous asteroid impact event triggered the mass extinction of the earth species Placenta mammals on Earth