Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Fossil = direct or indirect evidence of ancient life preserved in rockshttp://www.gc.maricopa.edu/earthsci/imagearchive/coprolite.jpggastrolithshttp://www.fossilmall.com/Fossil_Archive/Trace_Softbody_Fossils/Climactichnites/dfd100d-large.gifMost 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?How does a dead organism become a fossil?Modes of Preservation:1. original preservation (unaltered remains)http://www.ambermine.com/images/page1/18m.jpghttp://upload.wikimedia.org/wikipedia/commons/thumb/a/a4/Misc_pollen.jpg/290px-Misc_pollen.jpghttp://paleo.cortland.edu/tutorial/Taphonomy&Pres/Taph%26Pres%20Images/horseshoe.GIFModes of Preservation:2. altered remains (structurally or chemically altered)Direct Fossil EvidencePermineralizationDirect Fossil EvidenceReplacementhttp://www.gc.maricopa.edu/earthsci/imagearchive/cephalopod.jpghttp://paleo.cortland.edu/tutorial/Taphonomy&Pres/preservation.htmModes of Preservation:2. altered remains (structurally or chemically altered)Direct Fossil EvidenceCarbonizationhttp://paleo.cortland.edu/tutorial/Taphonomy&Pres/preservation.htmModes 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.jpgDirect Fossil Evidencemolds(internal mold shown here – outershell gone but internal septa visible)Direct Fossil Evidencecast and moldshttp://www.getyourwebsitehere.com/fossils/images/fos_0011a.jpgWhat do we use the fossil record for?1. Understand the evolutionary history of lifehttp://www.ruf.rice.edu/~leeman/GeoTimeSpiral.gifWhat 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 identifiedhttp://pubs.usgs.gov/gip/geotime/fossils.gifWhat do we use the fossil record for?3. Interpreting past environmentshttp://www.wsgs.uwyo.edu/Coal/coal_brochure/images/fig1_swamp.jpghttp://oceanworld.tamu.edu/students/coral/images/coral_reef_1.jpghttp://www.geology.ohio-state.edu/~vonfrese/gs100/lect29/xfig29_02.jpgHow are fossils classified?http://www.anselm.edu/homepage/jpitocch/genbios/25-07-HierarchicalClass-L.jpgBased on morphology (shape) and inferred phylogenic (family tree)