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Unformatted text preview: Evolution and Classification of Animals Animals probably evolved from marine protists , although no group of protists has been identified from an at-best sketchy fossil record for early animals. Cells in primitive animals (sponges in particular) show similarities to collared choanoflagellates as well as pseudopod-producing amoeboid cells. Multicellular animal fossils and burrows (presumably made by multicellular animals) first appear nearly 700 million years ago, during the late precambrian time (the part of the Proterozoic era termed the Vendian). All known Vendian animal fossils had soft body parts: no shells or hard (and hence preservable as fossils) parts. Learn more about these early animal fossils at Learning About the Vendian Animals . Animals in numerous phyla appear at (or in many cases before) the beginning of the Cambrian Period, as shown in Figure 1....
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- Fall '10