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Types of Fossils


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Petrified Remains: process by which organic matter is replaced by minerals turning it into stone.

petrified wood
petrified wood

  the hollow shape in a rock left behind after an organism decays (think of the empty space in a baking pan).

trilobite mold


  sediments fill in the mold or space left behind in a rock by an organism, showing the same shape as the organism (3-D)


Mold and Cast

mold and cast

The fossil on the left is the MOLD and the fossil on the right is the CAST.

Carbonaceous Film: 
 heat/pressure force gases and liquids from an organism, leaving a thin film of carbon behind.

leaf carbon film insect carbon film

Trace Fossil: 
 mark or evidence of the activities of an organism.  Such as teeth marks, foot prints, burrows, and fossilized animal droppings.

trace fossil
trace fossil

Original Remains: 

Freezing:  freezing prevents substances from decaying.

frozen mammoth
frozen mammoth

  sticky resin from trees that traps an organism and hardens.

insect preserved in amber
insect preserved in amber

Tar Pits:
  large pools of tar that trapped animals when they went to drink the water that usually covered the pools.

tar pit
tar pit


Fossil Formation:

Fossils require 3 conditions to occur in order for the remains of an organism to become fossilized.

1.  Protection from decomposers (microorganisms, scavengers, and fungi)
Explanation:  Protection from decomposers will ensure that some of the organism remains to become fossilized.

2.  Quick burial under sediments.
Explanation:  A quick burial provides protection from decomposers.

3.  Presence of hard body or plant parts.
Explanation:  Hard parts are more likely to fossilize because they decay slowly.  Soft parts, such as skin and organs, decay very quickly and are rarely preserved (except in the case of original remains).



Fossil:  preserved remains or evidence of a once-living thing.

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