Evolution6 - Evolution #8, 9: Fossils: Precambrian &...

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The history of animals may span more than a billion years o o estimates that 99% of all animal species are extinct o studies estimate animal diversification >1bya, 1.5bya, 1.2b-800m ya o animal/fungi common ancestor: resemble modern choanoflagellates = protists that are the closest living relatives of animals, which was probably itself a colonial, flagellated protest o 4 geologic eras o Neoproterozoic Era (1b—542m ya) o Edicaran fauna: 1 st generally accepted fossils of animals 575myo o some appear to be related to living cnidarians (corals) o others represent soft-bodied mollusks o o also microscopic signs of early animals: 570myo embryos in China o end of this era was a time of rising levels of animal diversity o Paleozoic Era (542—251mya) o Cambrian explosion = early Cambrian period (542-424mya) of the Paleozoic
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Evolution6 - Evolution #8, 9: Fossils: Precambrian &...

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