Old and new species

  • Created by: Holly45
  • Created on: 23-03-15 18:11


  • remains of organisms from many years ago
  • they provide existence that organisms lived ages ago
  • many soft bodied animals left little traces behind
  • many fossils were destroyed by geological activities or haven't been found yet


  • things like teeth, shells and bones
  • they form a rock like substance shaped like the original part
  • surrounding sediments also turn to rock but fossil stays inside the rock


  • fossils form when the organism is buried in a soft material like clay
  • the clay will harden and a cast is formed


  • in Amber there is no oxygen or moisture so decay microbes can't survive
  • in glaciers it's too cold
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Extinction and speciation

  • extinction happens if you can't evolve quickly enough
  • many species become extinct because: the environment changes too quick, a new predator kills them, new diseases, they can't compete for food, catastrophic event kills them
  • speciation is the development of a new species
  • a species is a group of similar organisms that can reproduce to give fertile offspring
  • speciation occurs when population of the same species become so different that they no longer breed together to produce fertile offspring
  • isolation and natural selection lead to speciation
  • isolation is where populations of a specie are separated which can be due to a physical barrier
  • the conditions on either side are different
  • eventually individuals from either side will have changed so much that they can no longer breed with each other and become separate species
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