Mud Crab
Mud Crab - the perfect place to become a preserved fossil
An ancient mudcrab tells its story
My story - how I became a preserved fossil
Not all fossils are made of rock - some like me are made up of the original parts!
A preserved fossil is one where the hard parts remain intact and do not turn to rock themselves though the material surrounding them may turn to rock.
I was a mud crab living in a tunnel in the mud of an seaside swamp about 2 million years ago.
I lived in perfect conditions to become a preserved fossil near the sea namely:
- one day the sea moved away, who knows the reason why? and my mud quickly dried up
- surrounded by mud nothing could eat me or spread my shell around
- in very salty hot water not well liked by bacteria so my shell remained intact though my insides rotted away
- rotting vegetation made the mud low in oxygen so I was slow to break down
- my soft insides are gone, but my hard outershell remains, filled with mud hardened to rock
- while the mud around me turned to rock my original shell survived unchanged - so I am a preserved fossil, my original shell still intact after 2 million years!
You can learn some lessons from me about fossils...
- the fossil record is NOT a record of all the things that lived in the past - many soft bodied and delicate creatures may not be represented or are very rare in the fossil record
- the fossil record IS a collection of the most hard durable parts coming from environments most favourable to fossilisation
- big strong hard parts fossilise better than small hard parts
- so you CANNOT COUNT fossils to find out what was common and what was not
- for example dinosaurs were probably NOT very common, each would require a very large area for food, but the very durable hard parts DO collect in particular places making some people, such as movie producers, think they were common
- many of the fossils you see come from situations where it was easy to become a fossil - like rivers, lakes, sea shores
- few fossils are recovered from areas formerly woodlands, deserts, mountains, glaciers