Fossils

• How do fossils provide evidence for evolution?


  Fossils are remains of organisms from millions of years ago
• What is the definition of fossils?


  Fossils are the remains of organisms from millions of years ago found in rocks
• What are the three ways fossils can form?

  1. Parts of organisms not decayed, 2. Organism decays but parts replaced by minerals, 3. Preserved traces of organisms
• Under what conditions can parts of organisms not decay to form fossils?


  When temperatures are too cold, or there is not enough oxygen or water
• How can fossils form if an organism decays?


  Parts of the organism can be slowly replaced by minerals during the decay process
• What are some examples of preserved traces of organisms?


  Footprints of animals and preserved spaces where roots were
• Why are there very few fossils for early life-forms?


  Many early life-forms were soft-bodied and rarely formed fossils
• What is the impact of changes to rocks in the Earth's crust on fossils?


  Many fossils that formed have been destroyed by these changes
• What does it mean for a species to be extinct?


  A species is extinct when there are no remaining individuals of that species alive
• What are some reasons species can become extinct?


  Catastrophic events, environmental changes, and competition from new species
• How did the extinction of the dinosaurs occur?


  Due to a catastrophic event like an asteroid colliding with the Earth
• How can environmental changes lead to extinction?


  Changing weather patterns, new diseases, or new predators can kill all individuals of a species
• How can competition from new species lead to extinction?


  New, more successful species can compete for scarce food or water
• What are the key points about how fossils are formed?

  • Fossils can form when parts of organisms have not decayed.
  • Fossils can form if parts of the organism are replaced by minerals during decay.
  • Fossils can be preserved traces like footprints or root spaces.
• What are the main reasons for the scarcity of early life-form fossils?


  • Many early life-forms were soft-bodied and rarely fossilized.
  • Many fossils have been destroyed by changes in the Earth's crust.
• What are the different causes of species extinction?

  • Catastrophic events (e.g., asteroid impacts)
  • Environmental changes (e.g., weather patterns, diseases)
  • Competition from new species for resources