Tuesday, 20 September 2011

Exceptional preservation of fossils

Exceptonal preservation means that the fossils have very fine detail or the remains of soft tissues are preserved.

Ideal conditions
  • rapid burial- to protect hard parts from the destructive action of scavengers and the weather
  • burial in low- energy conditions for the best chance of fossilisation
  • lack of oxygen- anoxic
  • pH- decay is slowed down in conditions of high acidity- as in peat swamps 

Methods of exceptional preservation 

Amber - Amber is tree resin that has hardened and been preserved. when the resin was warmed in the sun, it flowed down the trunk. Animals become trapped in the resin , and where buried in later flows. the amber became harder due to chemical reactions . Amber is formed from the resin of the extinct pine tree called, Pinus succinifera.

Tar- tar pits formed when hydrocarbons that had migrated upwards formed pools of asphalt. water accumulated on top of the tar, forming a water hole which enticed animals.

The Burgess Shale -  The Burgess shale was dicovered in the canadian rocky mountains in 1909 by Charles Walcott, a famous geologist. The fossils are of Cambrian age and offer a snapshot into the evolution of life on earth. The animals found in this deposit are all extinct. some show similarities to animals that are alive today and may be distant relatives. There are many fossil Antropods, such as trilobites and lace crabs. The limbs, antennae,gills,gut and other soft tissues are replaced by a type of cly mineral.

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