Evidence for Evolution: Fossils

• What should you be able to do by the end of the video on fossils?

  Discover fossils, provide evidence for evolution, and explain how fossils are formed
• 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
• What conditions can prevent the decay of organisms leading to fossil formation?

  Cold temperatures, lack of oxygen, and lack of water
• Why are there very few fossils of early life-forms?

  Many early life-forms were soft-bodied and rarely formed fossils
• What happens to many fossils that did form from early life-forms?

  Many have been destroyed by changes to rocks in the Earth's crust
• 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 more successful species
• What catastrophic event led to the extinction of the dinosaurs?

  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 more successful species lead to extinction?

  More successful species can compete for scarce food or water
• What are the key points about fossil formation?

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

  • Difficulty in understanding how life on Earth began.
  • Limited evidence for the evolution of early organisms.
  • Challenges in reconstructing the history of life.
• What are the main causes of species extinction?

  • Catastrophic events (e.g., asteroid impacts).
  • Environmental changes (e.g., climate shifts, diseases).
  • Competition from more successful species.