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Unformatted text preview: ent types of fossils
Ice 1. Intact Resin (amber)
Volcanic ash La brea tar pits 8 Different types of fossils
2. Compression Crushed by sediments into thin film (organic material remains) 9 Different types of fossils
3. Impression Negative image of organism (no organic material remains) 10 Different types of fossils
Impression Compression 11 Different types of fossils
4. Cast After being buried, remains decompose and hole (mold) fills with dissolved minerals 12 Different types of fossils
5. Permineralized Minerals gradually seep into cavities and cellular spaces and harden.
Some organic material remains (e.g. Cell walls) 13 Different types of fossils
6. Petrification Permineralization followed by replacement (cast) of all organic material. 14 Different types of fossils
Digestive trace 7. Trace
Movement trace Predation trace Drill hole Repair
scar Worm burrows. A fossil of trace of an animal rather than of the animal itself. 15 Movement Trace Fossils Dinosaur tracks From Wilson et al. (2009) in PlosOne. 17 How are fossils aged?
Relative age Layers of accumulated rock mark
chronological order of occurrence 18 How are fossils aged?
Absolute age Refer to Figure 25.5 (Campbell 9th ed) ½ Life:
C14: 5,730 years
K40: 1.3 billion years 19 BUT the fossil record is a
NONRANDOM sample of the past
due to: 1. Habitat Bias
- Areas of high sediment accumulation (Beaches, mudflats, swamps)
- Burrowing organisms pre-buried
2. Taxonomic Bias
- Bones, shells and teeth vs. tissues
3. Temporal Bias
- Recent fossils:
- more common
- closer to surface
- less likely to have been destroyed
4. Abundance Bi...
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- Fall '10