Fossils

• Fossils - remains of organisms form millions of years ago found in rock.
• Ways of fossils forming;

  • Replaced by minerals (Minerals replace hard bones as they decay slowly).
  • Casts and impressions (Organism is buried in soft material and the material hardens as organism decays).
  • Preservation ( Animal gets stuck in amber or tar and is unable to decay due to no oxygen).
• Reasons for incomplete fossil records;

  • Early life was soft bodied so decayed quickly.
  • Fossils may have been destroyed or not found yet.
  • Geographical activity (movement of plates).
• Reasons why organisms go extinct;

  • Environment changes too quickly.
  • Habitat is destroyed.
  • Disease.
  • New predator.
  • New species which outcompete them.
  • Catastrophic event.