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A. The Fossil Record

A. The Fossil Record. The Law of Succession. pygmy armadillo. wombat. fossil glyptodont. fossil Diprotodon. The Fact of Extinction. Rivers carry sediment into seas and swamps. Layers of deposited sediment. Fig. 22- 3 Campbell and Reece. Younger stratum with more recent fossils.

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A. The Fossil Record

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  1. A. The Fossil Record

  2. The Law of Succession pygmy armadillo wombat fossil glyptodont fossil Diprotodon

  3. The Fact of Extinction

  4. Rivers carry sediment into seas and swamps Layers of deposited sediment Fig. 22-3 Campbell and Reece Younger stratum with more recent fossils Older stratum with older fossils

  5. 0 2 4 4 Bristolia insolens 6 4 8 Bristolia bristolensis 3 Fig. 22-15 10 12 Depth (meters) 3 Bristolia harringtoni 2 14 16 Bristolia mohavensis 18 1 3 2 Latham Shale dig site, San Bernardino County, California 1

  6. Fig. 25-4 Rhomaleosaurus victor, a plesiosaur Present Dimetrodon 100 million years ago Casts of ammonites 175 200 270 300 Hallucigenia 4.5 cm 375 Coccosteus cuspidatus 400 1 cm Dickinsonia costata 500 525 2.5 cm 565 Stromatolites Tappania, a unicellular eukaryote 600 3,500 1,500 Fossilized stromatolite

  7. Fig. 25-5 Campbell and Reece Accumulating “daughter” isotope Fraction of parent isotope remaining 1/2 Remaining “parent” isotope 1/4 1/8 1/16 4 3 2 1 Time (half-lives)

  8. Bias in the fossil record: Preservation bias Temporal bias

  9. Trends in Evolution

  10. Cope's rule: evolution tends to increase body size over geological time in a lineage of populations. Figure: over the last sixty million years, the average weight of horses has increased ten fold.

  11. Understanding the type of trend (passive or driven) is important Don’t over-interpret too much about mechanisms Selection can be going on in a passive system or in a driven one…

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