Describe the distinguishing organisms and major biological events associated with the following geological time

units.
A. Precambrian time
B. Paleozoic era
C. Mesozoic era
D. Cenozoic era What will be an ideal response?


Concepts to Consider: Precambrian--bacteria, protists, fungi and simple multicellular
animals. Paleozoic era--all major groups of plants (except angiosperms) and all animal phyla
appeared; also associated with the largest extinction event. Mesozoic--diversification of
reptiles, including dinosaurs, and the appearance of flowering plants, insects, birds, and early
mammals; a major extinction event, probably due to a meteor impact, resulted in a massive
extinction at the end of this era. Cenozoic era--continued diversification of flowering plants,
birds, insects, and mammals.

Biology & Microbiology

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