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28 Cards in this Set
- Front
- Back
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What is a fossil? |
Remains, or traces, of ancient life |
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How long is ancient? |
>10,000 years |
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Body fossil |
(Remains) the actual body or part of an organism, whether altered or not |
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Trace fossil |
(Traces) any evidence of past life that is not a body fossil (ex: casts, prints) |
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What are factors that increase the probability of fossil preservation? |
-hard parts (shells) -rapid burial (mass wasting) -anoxic environment (low oxygen) -minimal post-depositions alteration |
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How do body fossils get preserved unaltered? |
-original skeletal material -tar impregnation -amber emtombment -refrigeration -Mummification |
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What is recrystallization? |
Change in size and shape of crystals that make up skeleton, but not composition; often make larger crystals and destroys fine texture |
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Replacement |
Skeletal material is replaced, molecule by molecule, by a new mineral. This process occurs gradually over a long period of time as the original mineralogy dissolves away and a new mineral precipitates in its place (Ex: silicification, pyritization) |
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Permineralization |
(Filled with minerals) takes place in porous materials; minerals precipitate out of solution and fill in the pores and empty spaces-- leaves microstructure intact |
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Carbonization |
(Filled with minerals) organism becomes pressed into sediment and it's volatile, liquid or gaseous contents are forced out leaving a thin film of carbon |
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What is a mold? |
An impression; any reproduction of the internal/external surface of an organism |
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What is a cast? |
A duplicate of original; when original parts are dissolved away and space becomes filled either with sediment or mineral |
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What are some behavioral trace fossils? |
-boring and borrows -coprolites (fossilized poop) -gastroliths (stones animals swallow) -gnawings |
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What is taphonomy? |
Study of all the processes that combine together to form fossil deposits |
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What are the three stages of taphonomy? |
Biological/ecological- life history strategies, competition, predation Necrolysis- decomposition and decay after death, but before permanent burial; removes soft parts Biostratinomy- processes of bioerosion, transport, sedimentation, burial, and diagenesis (the physical and chemical changes occurring during the conversion of sediment to sedimentary rock) |
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Processes that form fossil deposits tend to _______ |
Mix organisms; would not ordinarily live together in same space or time |
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So a ______ ________ represents some interval of time. |
Fossil deposit |
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What is time averaging? |
The process of mixing fossils that have otherwise non-overlapping environmental, geographic, temporal, or evolutionary ranges |
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What is a snapshot in time averaging? |
Instantaneous; generations |
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How long does within-habitat mixing occur? |
100s to 1,000s years |
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How long does environmentally condensed time averaging occur? |
100s-1,000s of MA |
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How long is biostratigraphically condensed time averaging? |
10^5 to 10^8 years |
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Where do fossil deposits form? |
Most likely to form where: -sedimentation is regular (rapid burial) -oxygen concentration is low -necrolysis is slow ~ deep marine environment ~ lakes (stratified dysoxic) ~ streams |
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How complete is the fossil record? |
-~15 million described species in modern biota -~250,000 described fossil species -9 phyla with preservable hard exoskeleton -180,000 known species, 1,200,000 possible species over 600MA =>15% of all species that have ever lived have left a fossil record |
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What is the principle of similarity? |
"Things" that are similar are more closely related to each other than they are to things that are dissimilar |
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What is binomial nomenclature? |
All organisms are named with a latinized two-part name: Genus and Species |
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Why is taxonomy important? |
Is descriptive: all the characteristics of a species are documented. All of biology and paleobiology depend on accurate, stable taxonomy |
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What is classification? |
Process of arranging objects into groups or categories; modern technology allows science to further divide and classify species (DNA research) |
