Unformatted text preview: cross-section reconstruction 15 2/19/2008 Small Shelly Fossils Increasing diversity & abundance g y starting ~544 Ma mmmm-size skeletal fossils Tubes, cones, plates Many are parts of larger skeletons Mostly problematic (animals, but what kind?) Probably stem groups of modern phyla Cambrian radiation
Many modern phyla of animals appeared in the Early pp y Cambrian Many included taxa that evolved skeletons Not a uniform radiation (throughout the Cambrian) Lowermost: mostly simple skeletal fossils Tommotoian fauna
(small shelly fossils, but more complex) Within a few tens of millions of years, animals diversify at the phylum, class, and order level = adaptive radiation (more on this in a bit) And larger animals: some belong to phyla that have survived to the present 16 2/19/2008 Cambrian Lagersttten
(Lagersttten = fossil deposits of extraordinary richness or completeness) Cambrian Lagersttten preserves soft-bodied softorganisms The Burgess Shale and Chengjiang record the Cambrian Explosion Let's look into this preservation in a little more detail... Burgessochaeta, an annelid worm from the Middle Cambrian Burges...
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- Spring '08
- Geology, Cambrian, Cambrian Explosion, Snowball Earth, Ediacaran fauna