What Fossils Tell Us About Extinct Species

• What are fossils?


  Fossils are remains or traces left behind by long dead organisms.
• Why is studying fossils important?

  Studying fossils is important because most organisms that have ever lived are now extinct.
• What evidence do fossils provide for evolution?


  Fossils provide evidence for evolution by showing how organisms have changed over millions of years.
• What are the three main ways fossils can form?

  1. Gradual replacement by minerals
  2. Casts and impressions
  3. Preservation without decay
• How do gradual replacement fossils form?

  Gradual replacement fossils form when body parts decay slowly and are replaced by minerals, creating rock-like substances.
• What are casts in fossil formation?


  Casts are formed when an organism is buried in soft material, decays, and leaves a gap in the shape of the organism.
• What are impressions in fossil formation?


  Impressions are marks left by organisms, such as footprints, that remain over time.
• How can fossils form through preservation?


  Fossils can form through preservation when organisms are trapped in amber, tar pits, glaciers, or peat bogs, preventing decay.
• What is the age range of the oldest fossils found?


  The oldest fossils found are between three and a half to four billion years old.
• Why is there not a complete fossil record?


  There is not a complete fossil record because many early life forms were soft-bodied and decayed quickly.
• What geological events can destroy ancient fossils?


  Volcanoes, earthquakes, and tectonic plate movements can destroy ancient fossils.
• When can we say a species has gone extinct?


  A species is considered extinct when no individuals of that species remain.
• What are some reasons why species might go extinct?


  • Rapid environmental changes
  • Arrival of new predators
  • Human hunting
  • Spread of new diseases
  • Competition with new species
  • Catastrophic events (e.g., asteroid impacts)
• What catastrophic event is mentioned that led to the extinction of the dinosaurs?

  The asteroid that hit Mexico 66 million years ago led to the extinction of the dinosaurs.