GEOL 107 Lecture Notes - Lecture 11: Collagen, Apex Predator, Cambrian Substrate Revolution
6 Oct 2017
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The cambrian explosion - emergence of skeletons and brains (cowen, 2013, chapter 4, pp. Most profound and rapid diversification event (evolutionary radiation) in the history of life. Exponential rise in diversity throughout the early cambrian. Cambrian explosion mainly involves bilateria coelomates (have a coelome = internal fluid- filled cavity, see cowen, 2013, p. 48-50) Appearance of essentially all coelomic phyla (including our own) in 20-25 million years or less. **-reflects the emergence of skeletons and brains*: cambrian skeletons, proliferation of crown-group radial animals, especially sponges. Appearance of most of the classes of sponges (porifera) Archaeocyathan (heavily armoured sponges) were the first skeletal reef-builders, went extinct at the end of the early cambrian. Some shells were dwelling tubes and shells (e. g. clam and snail shells, molluscs) Most were sclerites (spines that armoured the body; wiwaxia, cowen, 2013, fig. Small shelly fossils were the dominant skeletons in the early cambrian, rare thereafter: small shelly fossils (several phyla, brachiopods.
