BIO 200 Chapter Notes - Chapter 25.3: Ape, Herbaceous Plant, Mesozoic
2 Sep 2016
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The history of life on earth - chapter 25. 3. What are the major events in life"s history. Biologists refer to the assemblage of all organisms of all kids living at a particular time or place as the biota. Plants living at a particular time or place are called flora. Animals living at a particular time or place are called fauna. Of the present-day biota, about 1. 8 million species have been named. Actual number of species is estimated to be in the tens of millions. Several processes contribute to the paucity of fossils. Organisms live and die in oxygen-rich environments. Fossilization can only occur if the carcass is transported via wind or water to a site that lacks oxygen. Fossils can be destroyed due to geological processes or are deeply buried and inaccessible. Fossil record for marine animals with hard skeletons is the most complete. Insects and spiders are also well represented due to their numerical abundance and hard exoskeletons.
