Fossils & Extinction

• Fossils are the remains of organisms from millions of years ago, which are found in rocks
• Why are fossils used to as evidence for evolution?

  Fossils show us how species have changed over millions of years
• Why is the fossil record incomplete?

  Some fossils formed long ago may have been destroyed since

  Some organisms are soft-bodied so do not fossilise well
• 1. Hard body parts, such as bones and shells, which decay very slowly, are gradually replaced by minerals, forming rock-like substances.
• Why might a dead animal be preserved in a tar pit, rather than decay?

  Not enough oxygen for decay to take place
• Suggest three ways a species may become extinct?

  Rapid environment change such as an increase in temperature

  Reduction in habitat as it could reduce food and living space

  Increase hunting as individuals are directly killed 

  The spread of a new disease 

  Introduction of a new competitor or predator 

  A catastrophic event, such as an asteroid strike