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FOSSILS

FOSSILS. Fossils. remains or imprints of an organism that lived long ago Formed 5 ways …. 1) In Rocks. Dead organism is buried in sediment. 2) Amber. hardened tree sap. 3) Frozen. Found in blocks of ice. 4) Petrification. Minerals replace tissues and become rock. 5) Asphalt/Tar.

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FOSSILS

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  1. FOSSILS

  2. Fossils • remains or imprints of an organism that lived long ago • Formed 5 ways ….

  3. 1) In Rocks • Dead organism is buried in sediment

  4. 2) Amber • hardened tree sap

  5. 3) Frozen • Found in blocks of ice

  6. 4) Petrification • Minerals replace tissues and become rock

  7. 5) Asphalt/Tar • La Brea Tar Pits in L.A. are at least 38,000 years old. • These pools have trapped and preserved many different organisms, like the saber-toothed cats & dire wolves.

  8. Types of Fossils

  9. 1) Trace Fossils • Clues made by an organism, but do not include parts of the organism’s body

  10. Other Examples of Trace Fossils • Burrows (shelters made by animals that bury themselves in the sediment) may be filled with sediment and preserved. • “Caprolites” = dung (“poop”) that is fossilized.

  11. 2) Molds • Mold = the print/impression left in sediment/rock where organism was buried.

  12. 3) Cast • Cast = forms when sediment fills a mold and becomes rock.

  13. How it is formed • http://www.oum.ox.ac.uk/thezone/fossils/intro/form.htm • http://www.brainpop.com/science/diversityoflife/fossils/

  14. What Can Fossils Tell Us? • The kind of organism • How the environment has changed (ex: forest fossils found in Antarctica show the climate was much warmer in the past) • How organisms have changed (evolved)

  15. How Old Is It? • To understand the history of the Earth, scientists have put fossils in order based on their ages. • They use relative dating and absolute dating methods

  16. Index Fossils • fossils are found only in rock layers of a certain age. • Ex: When scientists find Phacops in a rock layer, they know the rock layer is 400 million yrs old.

  17. Fossil Observation

  18. Whale Evolutionbased on fossils • Ocean adapted mammals • Embryos of several whales have well-developed rear legs that disappear • Fossils of modern whales are not so “modern”

  19. How did whales get here? • Primitive whales (#1) found in rocks about 36 mya

  20. Place Mesonychid at 55 mya level • Pakicetus (#3) was found in sediment 50 million years old. • Basilasaurus (#4) fossils found – 37 mya • Rodhocetus fossils in sediment 46 mya. • Where is the gap? Draw an intermediate stage of animal.

  21. Adaptations • Variations that help an organism survive and reproduce

  22. How does evolution occur?Theory of Natural Selection • Variations in species provide an advantage for survival = adaptations • Organisms with these variations are better adapted to their environment • These organisms get more food and reproduce more passing their traits on to their offspring • Over time a population changes based on these adaptations, eventually creating a new species

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