更奇特的是,据估计,这些足迹所在的岩石是在海平面至少一千米以下形成的。
Fossil bodies might get into such rock by sinking to the sea floor.
化石体倒是可能会沉到海底而进入这块岩石。
Tracks, however, must have been made by something that was alive.
然而,只有活的东西才能留下足迹。
Precambrian animals must therefore have lived at such depths.
因此,前寒武纪的动物肯定曾经生活在这么深的地方。
The tracks also cast light on what the Ediacarans actually were.
这些足迹也使我们了解了埃迪卡拉动物到底是什么。
Some palaeontologists think them members of a phylum that is now extinct.
有的古生物学家认为它们属于已经绝迹的一门动物。
Others, though, believe they were Cnidarians, the group that includes modern sea anemonesand jellyfish.
而有的则认为它们是刺胞动物,这是包括现代的海葵和海蜇在内的一门动物。
Cnidarians grow from embryos that have only two layers of cells.
刺胞动物是由只有两层细胞的晶胚发展而来的。
Most animals, including all the shelly Cambrian ones, grow from three-layered embryos.
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