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Fossil = direct or indirect evidence of ancient life preserved in rocks
http://www.gc.maricopa.edu/earthsci/imagearchive/coprolite.jpg
gastroliths
http://www.fossilmall.com/Fossil_Archive/Trace_Softbody_Fossils/Climactichnites/dfd100d-large.gif
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Most organisms that lived in the past left no record of their existence.
To become preserved as a fossil, an organism usually:
• Has hard parts.
• Is buried by sediment.
• Escapes physical, chemical, and biological destruction after burial.
BAD = burrowing (bioturbation), dissolution, metamorphism, or erosion
….A bias towards benthic (bottom dwelling marine life with hard parts)!
How does a dead organism become a fossil?
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How does a dead organism become a fossil?
Modes of Preservation:
1. original preservation (unaltered remains)
http://www.ambermine.com/images/page1/18m.jpg
http://upload.wikimedia.org/wikipedia/commons/thumb/a/a4/Misc_pollen.jpg/290px-Misc_pollen.jpg
http://paleo.cortland.edu/tutorial/Taphonomy&Pres/Taph%26Pres%20Images/horseshoe.GIF
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Modes of Preservation:
2. altered remains (structurally or chemically altered)
Direct Fossil EvidencePermineralization
Direct Fossil EvidenceReplacement
http://www.gc.maricopa.edu/earthsci/imagearchive/cephalopod.jpg
http://paleo.cortland.edu/tutorial/Taphonomy&Pres/preservation.htm
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Modes of Preservation:
2. altered remains (structurally or chemically altered)
Direct Fossil EvidenceCarbonization
http://paleo.cortland.edu/tutorial/Taphonomy&Pres/preservation.htm
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Modes of Preservation:
2. altered remains (structurally or chemically altered)
Direct Fossil Evidencemolds
(external mold shown here)
http://www.clas.ufl.edu/users/pciesiel/gly3603c/external.jpg
Direct Fossil Evidencemolds
(internal mold shown here – outershell gone but internal septa visible)
Direct Fossil Evidencecast and molds
http://www.getyourwebsitehere.com/fossils/images/fos_0011a.jpg
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What do we use the fossil record for?
1. Understand the evolutionary history of life
http://www.ruf.rice.edu/~leeman/GeoTimeSpiral.gif
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What do we use the fossil record for?
2. Determining relative ages of the rocks that contain them (biostratigraphy)and correlating rock units of the same age.
Index fossils - especially good fossils for this purpose• wide geographic range (swam or floated)• evolved rapidly• easily identified
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http://pubs.usgs.gov/gip/geotime/fossils.gif
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What do we use the fossil record for?
3. Interpreting past environments
http://www.wsgs.uwyo.edu/Coal/coal_brochure/images/fig1_swamp.jpg
http://oceanworld.tamu.edu/students/coral/images/coral_reef_1.jpg
http://www.geology.ohio-state.edu/~vonfrese/gs100/lect29/xfig29_02.jpg
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How are fossils classified?
http://www.anselm.edu/homepage/jpitocch/genbios/25-07-HierarchicalClass-L.jpg
Based on morphology (shape) and inferred phylogenic (family tree) relationships