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Evidence for Evolution

Evidence for Evolution. #1 — Fossil Evidence. Fossils are remains which have been buried for millions of years. Fossils show how organisms have changed over time. How a fossil is formed?. A dinosaur dies at a stream's edge .

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Evidence for Evolution

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  1. Evidence for Evolution

  2. #1 — Fossil Evidence • Fossils are remains which have been buried for millions of years. • Fossils show how organisms have changed over time.

  3. How a fossil is formed? A dinosaur dies at a stream's edge. Over time the body gets more buried, and it starts decomposing (rotting). The skeleton is left buried in a layer of sediment.

  4. As time goes on layers of rock are piled on top of the fossil.Where are the youngest strata? Where are the oldest strata? Youngest Layers Time Oldest Layers Strata = another word for layer

  5. #2 — Homologous Structures • Homologous = same • Homologous bones have the same basic shape in the same place, suggesting they share a common ancestor. Ex: Humerus, Radius, Ulna, Carpals, Phalanges

  6. #3 — Vestigial Structures • Vestigial = remaining • Vestigial structures are remains from early ancestors, but are no longer needed. Ex: Human Appendix Ex: Whale’s Leg Bone

  7. #4 — Geographic distribution • Where organisms live today is directly related to where their ancestors lived long ago when the continents were closer together. The dark green shows where ancient marsupials lived. Using knowledge about where continents used to be, scientists predicted that they would find marsupial fossils in Antarctica- and they did!

  8. #5 — DNA evidence • DNA of different species are very similar in sequence, suggesting they share a common ancestor. HOUSE CAT DNA TIGER DNA Ex: Tigers and house cats share 95% of the DNA base sequence.

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