Fossils:Fossils: evidence of past lifeevidence of past lifeRemains or traces of prehistoric lifeclick here for 9/page to printPetrifiedPetrifiedCavities and pores are filled with precipitated mineral matterppPetrifiedPetrifiedFormed by replacementCell material is removed and replaced withCell material is removed and replaced with mineral matterMoldMoldShell or other structure is buried and then dissolved by underground waterunderground waterhttp://www ammonoid com/Manning htmlShape is preserved in the surroundinghttp://www.ammonoid.com/Manning.htmlthe surrounding sedimentCastCast Hollow space of a mold is filled with mineral matterCarbonizationCarbonizationOrganic matter becomes a thin residue of carbon. This is a ‘compression’ of the original organismImpressionImpressionReplica of the fossil's surface preserved in fine-grained sedimenthttp://www.lfbuffalo.org/exhibitions/map/t/Preservation in amberPreservation in amberHardened resin of ancientHardened resin of ancient trees surrounds an organismIndirect Evidence Includes• Tracks• BurrowsC lit•Coprolites –fossil dung and stomach contentsg• Gastroliths stomach stones used to grind food by some–stomach stones used to grind food by some extinct reptilesTracksTracksDinosaur footprint in fine-grained limestone near Tuba City, Arizona.Types of fossils• Petrified • Carbonization • Formed by lt• Impressionreplacement •Mold• Preservation in amberMold•Castamber• Indirect evidenceConditions favoring preservation•Rapid burialRapid burial• Possession of hard partsFossils and correlationPi i l ff l i•Principle of faunal succession• Index fossilsPrinciple of faunal successionPrinciple of faunal succession•Proposed by William Smith py– late 1700s•Fossil organisms succeed•Fossil organisms succeed one another in a definite and determinable orderand determinable order, therefore any geologic time interval can betime interval can be recognized by its fossil contentcontenthttp://www.lfbuffalo.org/exhibitions/map/a/Archean through DevonianArchean through Devonianhttp://rst.gsfc.nasa.gov/Sect2/Sect2_1b.htmlCarboniferous through QuaternaryCarboniferous through Quaternaryhttp://rst.gsfc.nasa.gov/Sect2/Sect2_1b.htmlCambrian Marine LifeCambrian Marine Lifehttp://www.handprint.com/PS/GEO/geoevo.htmlTrilobiteTrilobitehttp://www.ststephens.it/biology/fossils.htmlOrdovician InvertebratesOrdovician Invertebrateshttp://www.handprint.com/PS/GEO/geoevo.htmlCrinoid380maCrinoid—380 mahttp://www.lsa.umich.edu/exhibitmuseum/exhibits/temporary_exhibits/Ordovician sea floorOrdovician sea floorhttp://www.uwsp.edu/geo/faculty/hefferan/Geol106/CLASS6/MAIN%20PAGE.htmSilurian reefSilurian reef• Silurian Reefhttp://hoopermuseum.earthsci.carleton.ca/camex/1rpaleoreef.htmlSilurian LandscapeSilurian Landscapehttp://www.nasa.gov/worldbook/earth_worldbook.htmlDevonian SeaDevonian Seahttp://www.handprint.com/PS/GEO/geoevo.htmlMid PaleozoicMid Paleozoichttp://www.tufts.edu/as/wright_center/cosmic_evolution/docs/text/text_bio_4.htmlLate PaleozoicLate Paleozoichttp://www.tufts.edu/as/wright_center/cosmic_evolution/docs/text/text_bio_4.htmlCarboniferous Fern ForestsCarboniferous Fern Forestshttp://www.handprint.com/PS/GEO/geoevo.htmlPermian SeaPermian Seahttp://www.handprint.com/PS/GEO/geoevo.htmlPermian ReptilesPermian Reptileshttp://www.handprint.com/PS/GEO/geoevo.htmlPermian ExtinctionPermian Extinction• Link to hypotheses of the Permian Extinctionhttp://en.wikipedia.org/wiki/Permian extinction• 80-95% of marine species died out70% f t t i l t b tppg_•70%+ of terrestrial vertebrates•Largest extinction episode in geologic a gest e t ct o ep sode geo og crecordGeologic time scaleGeologic time scale•Divides geologic history into units•Divides geologic history into units• Originally created using changes in organisms representing that time intervalintervalSubdivisionsSubdivisionsE•Eons–ErasEras• Periods–EpochsEonEonGreatest expanse of time: 4 eonsGreatest expanse of time: 4 eons•Phanerozoic ("visible life") –the aeooc( sbe e)emost recent eon: started 543 Ma• Proterozoic: 2500 – 543 MaA h 38002500 M•Archean: 3800 –2500 Ma•Hadeanoldest eon 45003800 Ma•Hadean –oldest eon 4500–3800 MaEras of the Phanerozoic eonEras of the Phanerozoic eon• Cenozoic ("recent life"): 65 Ma –now ()• Mesozoic ("middle life"): 248 – 65 Ma• Paleozoic ("ancient life"): 543 – 248 MaGeologic Time ScaleGeologic Time ScaleMesozoicMesozoichttp://geography.berkeley.edu/ProgramCourses/CoursePagesFA2002/Geog40/Geog40.Week7.htmlMesozoicMesozoichttp://serc.carleton.edu/introgeo/earthhistory/dinosaur.htmlMesozoicMesozoichttp://geography.berkeley.edu/ProgramCourses/CoursePagesFA2002/Geog40/Geog40.Week7.htmlMesozoichttp://www.tufts.edu/as/wright_center/cosmic_evolution/docs/text/text_bio_4.htmlAh tArcheopteryxhttp://www.researchcasting.ca/sculpt%20miami.htmMesozoic MammalMesozoic Mammal• Eomaiahttp://www.amnh.org/exhibitions/dinosaurs/diorama/Mesozoic MammalMesozoic Mammal• Repenomamushttp://www.amnh.org/science/papers/mesozoic_mammal.phpJurassicJurassichttp://www.worldbook.com/features/dinosaurs/html/world_mesozoic.htmlCretaceousCretaceoushttp://www.worldbook.com/features/dinosaurs/html/world_mesozoic.htmlMesozoic SeaMesozoic Seahttp://geography.berkeley.edu/ProgramCourses/CoursePagesFA2002/Geog40/Geog40.Week7.htmlMesozoic seaMesozoic seahttp://www.uky.edu/AS/Geology/webdogs/time/mesozoic/mesozoic.htmCretaceous ExtinctionCretaceous Extinction• Perhaps 60% of species died•Result of radical change in environmentResult of radical change in environment• Perhaps Earth encountered a large titmeteorite—–10 km in diameter– 90,000 km/hrEquivalent to100megatons of TNT exploding–Equivalent to 100 megatons of TNT explodingCenozoic mammalsCenozoic mammalshttp://www.handprint.com/PS/GEO/geoevo.htmlCenozoicCenozoichttp://www.handprint.com/PS/GEO/geoevo.htmlCenozoicCenozoichttp://www.uky.edu/AS/Geology/webdogs/time/cenozoic/cenozoic.htmCenozoicCenozoichttp://www.copyrightexpired.com/Heinrich_Harder/cenozoic.htmlRelative datingRelative dating Pl i k d t iPlacing rocks and events in proper sequence of formationDeciphering Earth’s history from clues in the rocksthe rocksLateral ContinuityLateral Continuityhttp://cse.cosm.sc.edu/hses/RelatDat/pages/lateral.htmPrinciple of Original Horizontality • Sediment is deposited phorizontally http://faculty.icc.edu/easc111lab/labs/labf/orig_horizontality.jpgPi i l fS
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