这些动物在白垩纪对气候变化不像今天这样敏感。
Scientists have linked the mass extinction at the end of the Cretaceous with a meteorite impact on Earth.科学家将白垩纪末期的大灭绝与地球上的陨石撞击联系起来。
This change in plankton found in marine deposits is what marks the boundary between the Cretaceous and the Tertiary.海洋沉积物中浮游生物的这种变化标志着白垩纪和第三纪的分界线。