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N. Adam Smith Postdoctoral Fellow National Evolutionary Synthesis Center

N. Adam Smith Postdoctoral Fellow National Evolutionary Synthesis Center. How do we Know ?. Measures of background radiation “cooling” and universal expansion rate agree that the Universe was formed ~13.7 Ga.

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N. Adam Smith Postdoctoral Fellow National Evolutionary Synthesis Center

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  1. N. Adam Smith Postdoctoral Fellow National Evolutionary Synthesis Center

  2. How do we Know ? • Measures of background radiation “cooling” • and universal expansion rate agree that the • Universe was formed ~13.7 Ga. • Our solar system must be at least as old as the oldest thing in it and there are meteorites that have been dated to ~4.8 Ga. • The oldest known rocks on Earth are at least ~4.0 Ga. Radioactive d

  3. Mars Rover Curiosity: landed 8/6/12

  4. 4.6 GaYears! (of Earth History)

  5. The Geologic Timescale

  6. Ammonites: go extinct 65 Ma along with non-avian dinosaurs

  7. Geologic time intervals are recognized by characteristic faunas. • Paleozoic (old life): lack of dinosaurs, mammals, flowering plants….abundant horn corals, trilobites, etc… • Mesozoic (middle life): “Age of the Dinos” • Cenozoic (recent life): “Age of Mammals”

  8. Major Evolutionary Events • Multicellular Life ~1 Gya (billion years ago) • Invasion of land by plants ~475 mya (million years ago) • Flowering plants ~130 mya • Demise of the dinos ~65mya (Chicxulub Crater) • Earliest “humans” ~5mya

  9. Issues with Faunal Correlation • ~75% of all rocks on Earth do not contain fossils • Fossils only give relative age, not absolute dates • Solution = radiometric dating

  10. The Geologic Timescale

  11. How does all of this geology relate to Evolution? • In general, evolution happens at timescales • outside of human ability to observe • (not true for many viruses for example) • This often leads to doubt and frequently prompts questions about transitional forms or so-called “missing links”

  12. Examples of “transitional forms” Archaeopteryx lithographica

  13. Examples of “transitional forms” Proto-whales with legs

  14. Examples of “transitional forms” Foraminifera (unicellular marine organisms)

  15. Summary • The Universe and the Earth are very, very old. • Geologic time is divided based on major evolutionary and geologic events. • Fossils provide relative dates and isotopes provide absolute dates. • Evolution happens on long timescales in most cases, but there are numerous examples of evolutionary change in the fossil record.

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