B2- old and new species


the origins of life on earth

  • earth began 4500million years ago and life on earth began 3500million years ago
  • we can date rocks by the fossils found in them
  • fossils can be formed by: hard parts of body not decaying
  • conditions for decay being absent 
  • parts of organism being replaced by other materials eg minerals
  • preserved traces of animals in mug 
  • many early life forms had soft bodies so they decayed
  • traces are likely to be destroyed by geologically catastrophes

fossil evidence

  • extinction means that a species that once existsted…


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