Post on 17-May-2015
FOSSILS: FORMATION AND CLASSIFICATION
By: Mr. Marjonlien A. Mahusay
FOSSIL - the remnants or trace of ancient living organisms
that has been preserved in rock or sediment
Kinds of rocks containing fossil
1. Sedimentary rocks
2. Volcanic ash deposits
Fossilization- process of forming a fossil
Kinds of fossils
2. Fossils preserved in an amber or tar
1. Frozen or dried bodies
3. Preserved or replaced bones, teeth and shells
4. Petrified (premineralized) organisms
Turn into stone
5. Mold and cast
6. Carbonized impressions
7. Trace fossils
Fossil preservation
1.Death in an anoxic (oxygen free) environment
2. Rapid burial
3. Presence of hard parts
Classifying fossils
• according to its morphology alone
Naming:• Compared fossil forms from known organisms
Ex. Fossil organize with spiral shell that does not contain internal chamber is classified as a member of class gastropoda
Trilobites- 3 segmented shell that is divided across its width into 3 parts (arthropod)
Gastropods (snails)- spiral shell, does not contain internal chamber
Bivalves (clams & oysters) – shells that can be divide into 2 similar halves
Common invertebrate fossil
Brachiopods – resemble screen like grid of cells
Crinoides – looks like a flower, stalks consist of numerous circular plates stacked on top of each other
Grapholites – tiny carbon saw blades in a rock
Ammonites – spiral straight shell that contains internal chambers and has ridge surface
Corals
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