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The Cambrian Explosion
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Lecture 17
3/27/98
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| | In the last two lectures, we looked at the fossil record from the late Precambrian and Cambrian times. |
| | Today we will use that record to look at the Cambrian Explosion. |
| | The Cambrian Explosion is a unprecedented time in the evolution of metazoans |
| | Our understanding of the Cambrian Explosion is evolving |
| | Small shelly fossils (ssf) |
| | Development of nearly all of the modern metazoan phyla |
| | slowly increasing O2 levels |
| | end of Precambrian glaciation at 600 my |
| Causes for the Cambrian Explosion |
| | Crossed a threshold value that allows hard part production |
| | Easier to have evolutionary experiments |
| | vertically burrowing organisms |
| | development of teeth/predatory lifestyle |
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