Types of fossil preservation

wastedshadows's version from 2016-01-23 10:56


Question Answer
Exclusion of oxygen, preservation of soft tissue. 1. Being frozen shortly after death. 2. Organisms being trapped in tree resin Unaltered soft parts
Soft tissue becomes mineralised soon after death, before decomposition can occur - hallucigenia in burgess shaleAltered soft parts
Hard shells and skeletons composed of stable compounds that wont break down easily after death - calcite shells of coralsUnaltered hard parts
Varying degree of alteration to original structure of hard parts - slight rearrangement of molecules - total removal of organic material Altered hard parts
Volatile organic constituents such as oxygen, hydrogen and nitrogen escape leaving a thin film of carbon on the rock - Didymograptus Altered hard parts - Carbonisation
Porous shells and bones made more dense by the deposition of minerals from percolating ground water. Original cellular structure can still be seen - petrified wood Arizona Altered hard parts - Permineralisation
Original microstructure is lost, hard parts converted into mosaic of interlocking crystals. Commonly maintains original mineral composition of involves a change from one mineral to another of simular composition but different structure - Aragonite to Calcite in corals Altered hard parts - Recrystallisation
Original microstructure may or may not be lost, all organic minerals replaced by others - Silicification in brachiopods Altered hard parts - Replacement

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