Ch12 earthandlifehistorysection2

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1. Evolution and Change ã Chapter Eleven: Evolution ã Chapter Twelve: Earth and Life History 2. Chapter Twelve: Earth and Life History ã 12.1 Evidence from Rocks…
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  • 1. Evolution and Change • Chapter Eleven: Evolution • Chapter Twelve: Earth and Life History
  • 2. Chapter Twelve: Earth and Life History • 12.1 Evidence from Rocks • 12.2 How Earth Changes • 12.3 Life History
  • 3. 12.2 How Earth Changes • Uniformitarianism refers to the use of features and process that are observable today, to interpret the ancient geologic record.
  • 4. 12.2 How Earth Changes • In 1915, Alfred Wegener (1880– 1930) theorized that the continents that we know today had been part of an earlier supercontinent. • He called this great landmass Pangaea.
  • 5. 12.2 How Earth Changes • To support his theory, Wegener observed that fossils of plants and animals found on different continents were very similar.
  • 6. 12.2 Plate tectonics • How the continents move is explained by a theory called plate tectonics.
  • 7. 12.2 Plate tectonics • The distribution of fossils provides evidence that the continents were once joined and have slowly separated over time. • Fossils of the same species have been found on several different continents.
  • 8. 12.2 Plate tectonics and fossil distribution • Glossopteris, an ancient plant species, was found on the continents of South America, Africa, India, and Australia. • If the continents are reassembled into Pangaea, the distribution of Glossopteris can be accounted for over a much smaller and connected geographic area.
  • 9. 12.2 Plate tectonics and fossils • One result of plate tectonics is the geographic separation of populations. • Separation of lithospheric plates separated the continents and divided populations.
  • 10. 12.2 Plate tectonics and evolution • Once populations became geographically separated they could no longer interbreed. • The separated populations evolved different adaptations. • Eventually, they became different species.
  • 11. Archaeology Connection • Imagine tiny humans that were only one meter tall - and that they hunted dwarf elephants that also lived on their island. A Tiny Challenge to Human History
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