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Unraveling Evolution: Fossils, Dating, and the Evidence of Change in Life Forms

This comprehensive overview explores the key concepts of evolution, emphasizing the fossil record as vital evidence. Fossils, preserved in sedimentary rock, reveal the timeline of life on Earth through stratification, where older fossils lie in lower layers. The geologic time scale categorizes eras such as Cenozoic and Mesozoic. We examine dating techniques, both relative and absolute, to establish the age of fossils. Furthermore, the mechanisms of evolution, including convergent and divergent evolution, are illustrated through examples like Caribbean Anole lizards and Darwin’s finches, showcasing adaptive radiation.

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Unraveling Evolution: Fossils, Dating, and the Evidence of Change in Life Forms

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Presentation Transcript

  1. Evidence of evolution • Fossil Record • Fossil- • Organism or evidence of an organism preserved in rock

  2. Fossil formation • Sedimentary rock • Superposition • Older fossils are found in lower layers of rock • Younger fossils in upper layers • Amber

  3. Geologic Time Scale • A time frame based on the fossil record • Eras (4) • Cenozoic • Mesozoic • Paleozoic • Precambrian • Periods • Epochs

  4. Dating • Determining the age of rock and fossils • Relative age • Used to determine the relative age • Compare layers of rock

  5. Dating • Absolute dating • (radioactive dating) • Used to determine the actual date • Uses the half life to determine actual age • Half life- time needed for half the radioactive atoms in a sample to decay • Carbon-14= 5,770 yrs • Uranium-238= 4.5 billion yrs

  6. Other evidence showing relationships • Comparative anatomy • Homologous structures • Vestigial structures • Comparative embryology • Comparative biochemistry

  7. Evolution in Action • Caribbean Anole Lizards • 3 species • On tree trunks & ground • On tree branches • On grass

  8. Evolution in Action • Other Islands show similar body types in other species of lizard • Convergent Evolution • Process where different species evolve similar traits

  9. Evolution in Action • Divergent Evolution • Process in which the descendants of a single ancestor evolve into species that fit different parts of the environment

  10. Evolution in Action • Adaptive Radiation • Species undergo divergent evolution until many parts of the environment are filled • Ex. Darwin’s Finches

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