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Definition
preserve some part of the organism itself, or its' shape.
Types:
unaltered preservation
desiccation
carbonization
alteration by mineralizing solutions
the actual organic remains of an animal, plant, fungus, algae, or bacterium |
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ONLY in perennially cold climates;
found in ice sheets/blocks |
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only happens to small organisms
Amount of actual tissue remaining in a specimen varies over time and conditions |
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| the oily fluids in tar seeps work into the bones, preventing them from being broken down by micro-organisms. |
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Definition
calcite skeltons of corals, bryozoans, and oysters are examples of some body parts of organisms that are already heavily mineralized and do not easily break down.
highly unusual
most informative!!
Happens when the hard parts of an organism are formed with a mineral stable enough to withstand the alteration effects within the buried rock
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Definition
occurs when the tissues of an organism get dried out, losing all their water. Become "mummified" through natural processes.
tissues dry out and are preserved that way |
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when distillation occurs, carbon concentrations are left behind as a thin film that preserves the shape of the otherwise soft body structure.
occurs when all organics leave the sediments except the carbon, which remains as a black film. |
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Definition
The original skeletal metrial is replaced, molecule by molecule by another mineral.
Common replacement minerals are silica, calcite, pyrite, limonite, and glauconite. |
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Definition
no destruction of the original skeleton; mineralized water flows through the porous skeleton and precipitates mineral deposits within the pores.
Occurs mainly in wood and vertebrate bone. |
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Definition
the original skeletal material alters in place into another mineral.
Common in corals, certain molluscs and other invertebrate groups
Recrystalliation requires the original material to recrystallize-- alering in place from one crstal form to another. this can be difficult to see without microscopic inspection, but will usually result in larger crystals in the fossil. |
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Definition
Fossils may be preserved in sperical or ellipsoidal nodules of hardened material.
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| indirect evidence of an organism, or evidence of the activity of past life. |
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| provide valuable insight into the behavior or locomotor techniques of organisms |
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| usually the traces of feeding behavior in soft, aquatic sediments |
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a hold drilled in a relatively hard surface such as a rock, hard bottom sediment, or skeletons of other organisms.
some gastropods and sponges bore into other objects or organisms. |
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| the skeleton of an organism is completely dissolved away, leaving an empty cavity in the rock. |
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| if sediments or minerals later fill the mold, a three-dimensional copy of the external surface of the object is created. |
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| internal mold (steinkern) |
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Definition
| a skeleton is filled with minerals or sediments. THEN the skeleton is dissolved, leaving a copy of the internal surfaces of the shell. |
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| highly polished, rounded stones sometimes found in association with archosaur skeletons. |
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- creatures that lack hard parts have a much lower likelihood of surviving these events.
-Organisms that live in high-energy or terrestrial environments are less likely to be preserved due to high amounts of erosion and slow burial time.
-Smaller organisms don't survive the rigors of transport, burial, and fossilization
-older fossils have a greater chance to be subducted so they have less chance to be preserved.
-rare organisms are less likely to be alive, thus less likely to be preserved.
-Certain fossils may get collected, catalogued, and deposited into the collection of a museum or institution more frequently than others.
- top predators will be preserved less often than their more numerous prey!
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