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Science

Old and new species

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Fossils provide a record of organisms that lived a long time ago. They also provide evidence that animals and plants can change over long periods of time. The fossil record is often incomplete. However, there is a good fossil record for the evolution of the horse.

Fossils

Fossils of ammonites - sea creatures that became extinct about 65 million years ago

Fossils are the preserved remains or traces of dead organisms [organism: A living being - plant, animal, fungus or bacterium. ]. They are found in rocks.

Fossils can be formed from:

  • Hard body parts, such as bones and shells, which do not decay easily or are replaced by other materials as they decay.
  • Parts of organisms which have not decayed. For example, dead animals and plants can be preserved in amber (hardened tree resin), peat bogs, tar pits or in ice
  • Casts or impressions, such as foot prints or burrows. These become covered by layers of sediment, which eventually become rock.

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Back to Speciation index

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