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FOSSILS & EVOLUTION

FOSSILS & EVOLUTION. How do we know that there was life millions of years ago?? BY: BRIANNA SHIELDS. DO NOW. Please place your take home test on your desk. GOAL. To define fossil and to determine which types of fossils are older based on layering

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FOSSILS & EVOLUTION

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  1. FOSSILS & EVOLUTION How do we know that there was life millions of years ago?? BY: BRIANNA SHIELDS

  2. DO NOW • Please place your take home test on your desk

  3. GOAL • To define fossil and to determine which types of fossils are older based on layering • To define evolution and the 4 ideas associated with the theory

  4. Relative Dating of Fossils Younger rocks (top layer) are found on top of older rocks (bottom layer) “LAW OF SUPERPOSITION” Ex: Diagram A Finding the Age of Fossils

  5. Index Fossils Fossils that lived during a short period of time Can help in aging rock Ex: Diagram E Which are index fossils? Which fossils are not as helpful for aging? Finding the Age of Fossils

  6. Fossil Age Rule A fossil is the same age as the rock that it’s found in Finding the Age of Fossils

  7. What have fossils told us? Life has existed on Earth for nearly 3 billion years Life on Earth: According to Fossils

  8. What have fossils told us? Life forms have changed (evolved) Life on Earth: According to Fossils

  9. What have fossils told us? Simple life began in water, evolved, became terrestrial Life on Earth: According to Fossils

  10. What have fossils told us? Some organisms have become extinct Trilobite, Woolly Mammoth, Dinosaurs Life on Earth: According to Fossils

  11. What have fossils told us? Some life forms have hardly changed Ex: Cockroaches, snails, snakes Life on Earth: According to Fossils

  12. Species A group of similar organisms that can interbreed to make fertile offspring Ex: All lions mate with one another Lions + Tigers = infertile Ligers or Tiglons Evolution

  13. Evolution A change in a species over time Use the camel evolution diagram Compare modern camels to their ancestors Evolution

  14. Evolution How has man changed over time? Evolution

  15. Lamarck’s Theory Theory of use & disuse An organism gets a new organ if it needs it Use it more & it will grow bigger New organ is passed to offspring What do you think about the validity of Lamarck’s Theory? Give an example Evolution

  16. Darwin’s Theory Theory of natural selection Better explanation of evolution The survival & reproduction of the organisms best adapted to their surroundings Evolution

  17. Theory of Natural Selection Part One: Survival of the Fittest Organisms overproduce offspring Organisms that are better competitors or more fit, will survive Parts of the Theory of Natural Selection

  18. Ex: Survival of the Fittest • Dandelions produce many seeds • This ensures some will live- others will not be able to find enough food & sunlight

  19. Ex: Survival of the Fittest • Tadpoles- many hatch at once • Fierce competition- stronger, faster ones will find food faster & outrun enemies

  20. Theory of Natural Selection Part Two: Variation & Adaptation Offspring that survive have structures or ADAPTATIONS that make it more fit for its environment Certain differences or variations help some to outcompete others Even within a species Ex: Finch Beaks Parts of the Theory of Natural Selection

  21. Variations in Finch Beaks

  22. Variations in Beaks and Feet

  23. Variation & Adaptation Example • How would a variation in polar bear coats help certain polar bears to have greater fitness? • There are variations in polar bear coats • Some polar bears have thicker coats of fur than others= better protection to cold • They are more likely to survive- this adaptation to their surroundings makes them a better competitor

  24. Variation & Adaptation Example • What happens to the fitness of a thick coated polar bear if the environment become warmer? • Which type of polar bear has the better variation in coat? • “The fittest that survive may change with their surroundings”

  25. Part Three: Reproduction Individuals that are more fit: Survive longer Reproduce more Pass on the beneficial traits or differences Evolution Library: Topic Page Parts of the Theory of Natural Selection

  26. Causes of Evolution Mutations or natural accidental mistakes in the animal’s DNA What causes evolution?

  27. Causes of Evolution Negative Mutation: Organism dies because it can’t compete (extinction) Positive Mutation: Organism becomes a better competitor- increases survival & reproductive chances What causes evolution?

  28. Extinction Occurs when many small adaptations occur over time (or negative mutations) Those with new adaptations outcompete old “versions” of the species Extinction

  29. Assessment • A hummingbird’s beak, giraffe’s neck & vampire bat’s teeth all help them to do what better? • What are adaptations- how do they affect the organism?

  30. Evolutionary Evidence 1. Fossil Record- documents the change in organisms over billions of years Evidence Supporting Evolution

  31. Fossil Evidence

  32. Evolutionary Evidence 2. Anatomical Evidence- similar body structures Homologous Structures= similar body parts that evolve suggest common ancestry Evidence Supporting Evolution

  33. Homologous structures • What similarities do you see among the structures in diagram B? • What do these homologous structures indicate?

  34. Homologous Structures

  35. Evolutionary Evidence 3. Embryological Evidence- similarities in the embryos of very different organisms Evidence Supporting Evolution

  36. Evolutionary Evidence 4. Chemical and Molecular Evidence The more similar the DNA code, the more closely related two organisms are Evidence Supporting Evolution

  37. DNA Homology

  38. Peppered Moth Scenario • Look at drawing on side board • Nowhere to Hide

  39. Peppered Moth Scenario • Which moth ended up being more “fit” or a better survivor or competitor? Why? • Answer the questions on your peppered moth sheet

  40. Websites • “Becoming Human” interactive documentary • BBC- Burying Bodies • BBC- Making Fossils

  41. Explain why many animals/plants don’t become fossils? Many remains are crushed, ruined, eroded, rotted, eaten or burned before they become fossils Assessment

  42. What types of objects make the best fossils? Hard parts- teeth, shells, bones, wood Assessment

  43. Describe where most fossils are formed and how they actually form. Many fossils form in sedimentary rock that used to be covered by oceans. When organism dies, gets buried by sediment in ocean, soft parts rot, hard parts preserved by sediment Assessment

  44. Tell about the difference between a mold and a cast Mold is hollow space left in sediment when animal rots, cast is when mold gets filled back in with other sediment Assessment

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