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Lecture 1

ANT203H5 Lecture Notes - Lecture 1: Coprolite, Paleontology, Paleomagnetism


Department
Anthropology
Course Code
ANT203H5
Professor
Esteban Parra
Lecture
1

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8.Introtopaleoanthropology
● Whatispaleoanthropology
○ Thestudyofhumanevolution,comprisingbothhomininbiologyandculture
○ Anthroman
○ Logiathestudyof
● Differentrolesofscientists
○ Geologistssurveys,locationofearlyhomininsites
○ Paleontologistssurveywork,knowledgeoffaunalremainsfoundinthearea
○ Archaeologistssearchformaterialculture(stonetools)togiveuscluesabout
homininbehaviour
● Evidenceofourancientpast
○ Skeletalandarchaeologicalremains
■ Bones
■ Tools
■ Footprints
■ Firepitsorhearths
■ Cutmarksonbones
● Whatisafossil
○ Physicalremainsortracesofananimalsbehaviourpreservedinrock
○ Theonlydirectevidenceofpastlife
○ Fossilizationisrareanddependentonanumberofimportantfactors
■ Geologicalfactors;natureandcompositionofsediments
■ Temporalfactors;variationinpreservationthroughtime
■ Biologicalfactors:exposuretootherorganisms
○ Taphonomyisthestudyofprocessesaffectinganorganismafterdeaththatmay
resultinitsfossilization
● Fossilization
○ Dieorloseteethwherethereisanabundanceofsedimentdeposition
○ Beburiedquicklyrapidburialpreventsdecay
○ Donotdecomposequickly(oxygen,humidityandrapiderosionisbadfor
fossilization)
○ Environmentisveryimportant,asisthesizeofthedeadorganism
○ Bediscovered–mostlikelyonlyfragmentswillbefound
● Homininfossils
○ Mosthomininfossilshavebeenfoundin
■ Volcanicdeposits:commoninEastAfricarapidburialofanimalsbyash
andvolcanicmudflows
■ Lake(lacustrine)orriver(fluvial)sedimentsrapidburialofanimalsinsilt
orclayviafloodingevents
■ Caves:commoninSouthAfrica
● Typesoffossils
Tracefossils:recordsofanorganism’sbehaviour
■ Biologicallygeneratedsedimentarystructures
■ Footprints,trackways,burrows,feedingmarks,coprolites,nests
Bodyfossils:physicalremainsofanorganism
■ Usuallyonlyorganismswithhardpartscanbepreserved
■ Sometimesperfectconditionsallowforsofttissuepreservation

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● Modesoffossilization
Replacement
■ Completeremovaloforiginalhardpartsbysolutionanddepositionofa
newmineralfromsurroundingsoil
■ Example:Paranthropusaethiopicus–the“BlackSkull”from
manganeserichsoil
CastandMold
■ Mold:Animpressioninsediment
■ Cast:Moldfilledwithsediment
■ Externalmolds:showexternalfeaturesofhartparts–e.g.shells
■ Internalmolds:showinternalfeatures
● e.g.Taungchildanditsendocast
Impression
■ Twoorthreedimensionalimprintsmostcommonlyfoundinsiltorclay
■ Example:LaetoliFootprints(3.6mya)–Australopithecusafarensis
● Datingthefossils
Relativedatingmethods
■ Relativeageofafossilorartifactwithreferencetoanotherfossil,artifact,
orevent.Noabsolutedates.
Chronometric(orabsolute)methods
■ Theyprovideestimatesoftheactualageofthematerial
○ Researchersusuallycombineanumberofmethodstoaccuratelyestimatethe
ageofahomininsite/fossil
● Relativedatingmethodexamples
○ Stratigraphy
■ Studyofrocksandlayers
■ Canbeproblematicwhentherearegeologicalorbiologicaldisturbances
● E.g.Folding,faulting,bioturbation
○ Biostratigraphy/faunalcorrelation
■ Relativedatingofhomininfossilscanbecarriedoutusingindexfossilsof
animalsthatlivedonlyduringaspecificperiodoftimeinthepast
■ Thebestindexfossilsaredistinctive,widespread,abundantandlimitedin
geologictime
○ Paleomagnetism
■ Basedonconstantlyshiftingnatureofearth’smagneticNorthpole
■ Whenlavacoolsdown,ironparticlesbecomemagnetizedandaligned
accordingtothepositionoftheNorthpoleatthetime
■ Reversalsand‘normal’magneticperiodsarewelldocumentedanddated
■ Homininfossilscanbedatedwithrespecttoknownmagneticreversals

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Theironparticlesmaintainsthedirectionoftheirmagnetismassoonastheycool,sowhilethe
metalsintherocksstillreacttothemagnets,thedirectionwillbesetoncetherockcools.Ifthe
rocksheatupagain(duetoanothervolcaniceruptionorsomethinglikethat),thenitwillaffect
thedirectionofmagnetism.
○ Fluorineanalysis
■ Basedonchemicalchangesofskeletalremainsburiedintheearth
■ Fluorineisanelementthatisfoundingroundwater.Withtime,theamount
offluorineintheboneincreasesandtheamountofnitrogendecreases
■ Onlyusefulwhenbonesarefoundatthesamelocation
● Chronometric/absolutedatingmethods
○ PotassiumArgondating
■ Usedtodateveryoldsites(severalmillionyearsold)
■ BasedonthetransformationofPotassium40intoArgon40
■ Halflifeofpotassiumis1.26billionyears
■ Usually,thePotassiumArgonmethodisusedtodatevolcanicrockorash
deposits,notbone
○ Radiocarbon(C14)dating
■ Usedtodaterelatively“young”sites;organicmaterial:5060kya
■ BasedondecayofCarbon14,whichhasahalflifeof5730years
■ Carbon14isproducedintheatmosphere,andisabsorbedbyanimals
andplants.Atdeath,theprocessofdecay(Carbon14toNitrogen14)
begins
○ Fissiontrackdating
■ Usedcommonlytocrosscheckpotassiumargon
■ BasedonthefactthatthefissionordecayofUranium238leavesatrail
(ortrack)ofdamageonthecrystalsofminerals
■ Thesetracksarecreatedataconstantratethroughtime,makingit
possibletodategeologicalstrata
● Choosingadatingmethod
○ Theselectionofwhichmethodtouseisbasedontwomainfactors:
■ Theapproximatetimerangeofthesite
■ Thetypesofmaterialsavailablefordating
9.Primatefossilrecordearlyprimateevolution
● Paleoanthropology:thestudyofancienthumanshomininevolution
● Multidisciplinaryscience:
○ Biologicalanthro
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