.2 fossil

• Fossils are the ‘remains’ of organisms from millions of years ago, which are found in rocks
• Fossils may be formed:

  from parts of organisms that have not decayed because one or more of the conditions needed for decay are absent

  when parts of the organism are replaced by minerals as they decay

  as preserved traces of organisms, such as footprints, burrows and rootlet traces
• The oldest known fossils date back to about 3500 million years ago.
• Some fossils can only be seen using special techniques like X-rays, electron microscopes and CT scans (computerised tomography). These techniques allow scientists to see inside objects without damaging them.
• Some fossils can tell us how an animal lived, what it ate and where it lived.
• Fossils also show changes over time – some species become extinct while others evolve into new ones.