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What do the Footprints Say???

What do the Footprints Say???. Mission. Reconstruct happenings from the geological past by analyzing a set of fossilized tracks Form defensible explanations of past events from limited evidence . As more evidence is available, modify or abandon your hypotheses.

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What do the Footprints Say???

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  1. What do the Footprints Say???

  2. Mission • Reconstruct happenings from the geological past by analyzing a set of fossilized tracks • Form defensible explanations of past events from limited evidence. • As more evidence is available, modify or abandon your hypotheses.

  3. Position #1 • Can you tell anything about size or nature of organisms? • Were the tracks made at the same time? • How many animals involved? • Can you reconstruct a series of events represented by this set of fossil tracks? • Suggest evidence to support your explanations!

  4. Position #2 • With new info, revisit first explanation • MODIFY your explanation and/or add newones

  5. Interpret What Happened

  6. Questions to Consider... • In what directions did animals move? • Did they change speed or direction? • What might have changed the footprint pattern? • Was the land level or irregular? • Was the soil moist or dry? • In what kind of rocks were the prints made? • Were sediments coarse or fine? • Characteristics of track environment?

  7. Remember! • Any reasonable explanation must be based only on those proposed explanations that still apply when all of the puzzle is projected

  8. For Each Explanation... • Be sure to indicate the evidence! If you could VISIT the site, what evidence would you look for to support your hypothesis? Adapted from a BSCS lab

  9. LS Chapter 5-2 Notes The Fossil Record

  10. What is a Fossil? • Fossil – preserved remains or traces of an organism that lived in the past. • Most fossils form when organisms that die become buried in sediments.

  11. What Do Fossils Reveal? • Fossil record – millions of fossils that scientists have collected • Extinct – if no member of that species are still alive. • Most of what scientists know about extinct species is based on the fossil record. • Fossil record also provides clues about how and when new groups of organisms evolved.

  12. How Fast Does Evolution Occur? Two Theories • Gradualism – tiny changes gradually add up to major changes over very long period of time • Intermediate forms appear • Punctuated Equilibria – evolution occurs during short periods of rapid change separated by long periods of little or no change. • No intermediate forms appear

  13. Other Evidence for Evolution

  14. Appendix – appendicitis

  15. Scientists compare body structures, development before birth, and DNA sequences to determine the evolutionary relationships among organisms

  16. Similarities in Body Structure • Homologous structures – similar structures that related species have inherited from a common ancestor

  17. Similarities in Early Development • Early embryonic stage • In early development, organism go through similar stages.

  18. Similarities in DNA • Method: Extracting DNA to compare. • The more similar the sequences, the more closely related the species are. • Question: Which animal are closer related? • Rodent; Elephant Shrew; Elephant

  19. Combining the Evidence • Scientists combined evidence from • Fossils • Body structures • Early development • DNA and protein sequences • In most cases, DNA and protein sequences have confirm conclusions based on earlier evidence.

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