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Unformatted text preview: animal phyla, this is the only phylum that does not have representatives appearing during the Cambrian. Brachiopods were present (although not major organisms in the environments) during the Cambrian, but after the Cambrian extinction, they underwent an adaptive radiation in the Ordovician. Brachiopods have bilaterally symmetrical shells, which make them among the most common marine fossils in Paleozoic rocks. Traditionally brachiopods were divided into articulate and inaticulate groups, depending on the presence or absence (respectively) of a hinge between the halves of the shell. The earliest brachiopods were inarticulated, and lacked that hinge. Lingula is an example of this type, with fossils very similar to that genus being found in Cambrian rocks, and persisting even today. Systematics of the brachiopods has been under intense revision lately, and the traditional split of the two groups may not in fact be a natural characteristic useful in taxonomy....
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- Fall '10
- Biology, Ordovician, Cambrian, Cambrian Period, brachiopods, ordovician period, reef building biota