Fossils and extinction

• How are fossils made?

  1. Traces of an organism may be preserved in rocks, called 'trace fossils'
  2. Hard parts of an animal may not decay easily, and forms a fossil
  3. Parts of an organism may be replaced by other materials as they decay, called 'mineralisation'
  4. Some parts of an animal do not decay because conditions are not suitable for decay organisms
• Comparing fossil remains with present day plants and animals can show us how much organisms have changed. This can be used as evidence for evolution.
• Fossil limitations are when there are gaps in fossil records.
• What are the 4 ways of extinction?

  1. The environment may change and organisms cannot adapt
  2. Organisms may be eaten by a new predator
  3. A new disease may kill them
  4. A new, more successful competitor may arrive in the habitat