TestingthemethodologicalutilityoftraceelementanalysisfordetectingdietarydifferencesinfossilfaunafromTurkana

ChristinaRyder1,RhondaQuinn2,3,JasonLewis4,5,Jean-PhilipBrugal6,SoniaHarmand4,5,7,HélèneRoche7,FrederickKyaloManthi8,MatthewSponheimer1

Introduction

1DepartmentofAnthropology,UniversityofColoradoatBoulder,2DepartmentofSociology,Anthropology&SocialWork,SetonHallUniversity,3DepartmentofEarthandPlanetarySciences,RutgersUniversity,4DepartmentofAnthropology,StonyBrookUniversity,5TurkanaBasinInstitute,6Universitéd’Aix-Marseille,CNRS,LAMPEA, 7CNRS,Maisondel’Archéologieetdel’Ethnologie,UniversitéParisOuest-NanterreLaDéfense,8DepartmentofEarthSciences,NationalMuseumsofKenya

NachukuiFormation,WestTurkana,Kenya

Traceelementanalysis(Sr/Ca,Ba/Ca,Mg/Ca)hasbeenutilizedtogaugedietinfossilhominins1,2,3,4,5.BiopurificationofSr,Ba,Mg,relativetoCa,increaseswithtrophicspaceandconsequentlycarnivoresexhibittraceelementratioslowerthansympatricherbivores6,7,8,9.PreviousworkhascharacterizedSouthAfricanecosystemsandhasbeenusedtoinfermeatconsumptioninAustralopithecusandParanthropus2,4,5.TraceelementratiossuccessfullyparsedouttrophiclevelinaneasternAfricanmodernmammalianecosystem(Laikipia,Kenya)10.Previousworkfoundbrowsers(adietcomprisedofSr,Badepletedleaves)displaylowSr/Ca,Ba/Cadietaryvaluesrelativetosympatricgrazers1,2,3.Yetcontrarytopreviouswork4,ourmodernstudyineasternAfricafoundnosignificantseparationamongherbivoroustaxa.HerewepresentapilotstudyineasternAfricaassayingtherelationshipbetweenSr/Ca,Ba/CavaluesinherbivorousfossiltaxatodetermineifthemodernfaunalpatternfoundinLaikipia,Kenyapersiststhroughtime.

TheNachukuiFormation,oneofthreemainformationsintheupperpartoftheTurkanaBasin,issituatedwestofLakeTurkanaandencompassessedimentsdatingtothePlio-Pleistocene11.TheNachukuiFormationiscomprisedofeightmembersandrangesinagefrom4Mato0.7Ma.

Numeroushominin-bearingarchaeologicalsitesarefoundwithintheNachukuiFormationincludingLokalalei1a(earlyHomo)12,NaiyenaEngol(Homo)13,andKalokodo6(Paranthropusboisei)13.Faunaincludedinthestudyarefromelevensites:Lomekwi3,Nasura1,Nasura2,Nasura3,Lokalalei1,Lokalalei2C,NaiyenaEngol1,NaiyenaEngol2,Nadung’a3,Nachukui6,Kalokodo6.SitedatesfromRoche(2011)andChrisLepre (pers.comm).

NSFprovidedfundingforstudenttraininginanthropologicalisotopicmethodologies(toRQ,NSF-BCS1455274).SetonHallUniversityResearchCouncilprovidedtravelfundstoRQforsamplecollection.

Results:Ba/CaHerbivoreSiteComparisons

Results:Sr/CaHerbivoreSiteComparisonsNaiyena Engol 1

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0Column 2

GrazerMixed Feeder

GrazerMixed Feeder

NaiyenaEngol1 Lokalalei 1

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5Column 2

GrazerMixed Feeder

GrazerMixed Feeder

Lokalalei1Lokalalei 2C

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5Column 2

BrowserGrazer

BrowserGrazer

Lokalalei2C Lomekwi 3

3

4

5

6

7

8Column 2

BrowserGrazerMixed FeederBrowserGrazerMixed Feeder

Lomekwi3 All Sites

1

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6

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8Column 2

BrowserGrazerMixed FeederBrowserGrazerMixed Feeder

AllSitesNaiyena Engol 2

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2.5

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3.5

4.0

Column 2

BrowserGrazer

BrowserGrazer

NaiyenaEngol2

Siteswithaminimumoftwoherbivorousdietgroups(browser,grazer,mixedfeeder)arepresentedwithboxplotsintheabovefigure.

NaiyenaEngol1 Lokalalei1 Lokalalei2C Lomekwi3 AllSitesNaiyenaEngol2Naiyena Engol 1

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0.6

0.8

1.0

1.2

1.4

1.6

1.8Column 2

GrazerMixed Feeder

GrazerMixed Feeder

Naiyena Engol 2

0.25

0.50

0.75

1.00

1.25

1.50

1.75Column 2

BrowserGrazer

BrowserGrazer

Lokalalei 1

0.0

0.5

1.0

1.5

2.0

2.5

3.0Column 2

GrazerMixed Feeder

GrazerMixed Feeder

Lokalalei 2C

0.0

0.2

0.4

0.6

0.8

1.0

1.2Column 2

BrowserGrazer

BrowserGrazer

Lomekwi 3

0.5

1.0

1.5

2.0

Column 2BrowserGrazerMixed FeederBrowserGrazerMixed Feeder

All Sites

0.0

0.5

1.0

1.5

2.0

2.5

3.0Column 2

BrowserGrazerMixed FeederBrowserGrazerMixed Feeder

Siteswithaminimumoftwoherbivorousdietgroups(browser,grazer,mixedfeeder)arepresentedwithboxplotsintheabovefigure.

Site Difference TestStatistic p-level

NY1(Grazer-MixedFeeder) 1.2971 0.7646 0.4463

NY2(Browser-Grazer) 2.0389 29.9327 0.1151

LA1 (Grazer-MixedFeeder) 0.2432 0.2120 0.6523

LA2C (Browser-Grazer) 3.0420 1.4647 0.2717

LOM-3(Browser-Grazer-MixedFeeder) 0.2480 0.7822

AllSites(Browser-Grazer-MixedFeeder) 0.0286 0.9718

Site Difference TestStatistic p-level

NY1(Grazer-MixedFeeder) 0.5042 0.5227 0.5220

NY2(Browser-Grazer) 1.0401 4.4634 0.2814

LA1 (Grazer-MixedFeeder) 0.5122 1.4199 0.2532

LA2C (Browser-Grazer) 0.9681 1.0887 0.3370

LOM-3(Browser-Grazer-MixedFeeder) 0.0139 0.9862

AllSites(Browser-Grazer-MixedFeeder) 0.8468 0.4333

0

0.2

0.4

0.6

0.8

1

forest

woodland

grassywoodland

woodedgrassland

grassland

Lomekwi(3.4-3.2Ma)14

Lokalalei(2.4-2.3Ma)15

Nasura(2.3-2.0Ma)16

NaiyenaEngol(1.8-1.6Ma)15

Nariokotome(1.6-1.4Ma)15

n=23 n=8

n=18

n=18

n=8

ChangingWoodyCoverintheNachukuiFormation

Fractio

nofW

oodyCover

openwoodedgrassland

FutureDirections:Indicatorsoftrophiclevel

VegetationStructureoftheNachukuiFormation

MonitoringDiagenesis

MassSpectrometry

DietCategories

WeanalyzedSr/CaandBa/Cafrombulkenamelof87individualswiththirty-nineandforty-eightspecimensidentifiedatthetribeandfamilylevel,respectively.DietcategoriesincludeC4 grazers,C3browsers,mixedC3-C4feeders,carnivores,andomnivores.

EnamelsampleswereanalyzedattheDepartmentofEarthandPlanetarySciencesatRutgersUniversity.TraceelementswereanalyzedonaThermoiCapQc ICP-MSunderthedirectionofJakeSetera;δ13CvalueswereanalyzedonaFISIONSIRMSunderthedirectionofJimWrightandRickMortlock.

Dietaryclassificationforeachspecimenwasconfirmedbyaδ13Cvalue.Above,themostcommondietislistedforeachtaxon,andthelesscommondietisinparentheses.

Sr/Ca

5.0

5.2

5.4

5.6

5.8

6.0

6.2Taxa

Felidae PantheraPapionini Papio

FelidaePanthera

Papionini PapioSr/Ca

Kalokodo 6

WefoundnosignificantdifferenceinSr/Caamongherbivoroustaxaatindividualsites(NY1,NY2,LA1,LA2C,LOM3)orwhenallsiteswerecombined.SimilartothefindingsinLaikipia,Kenya,Nachukui fossilC3 browserandC4 grazerSr/Ca ratiosdonotdifferfromoneanother.

WefoundnosignificantdifferenceinBa/Caamongherbivoroustaxaatindividualsites(NY1,NY2,LA1,LA2C,LOM3)orwhenallsiteswerecombined.SimilartothefindingsinLaikipia,Kenya,Nachukui fossilC3 browserandC4grazerBa/Ca ratiosdonotdifferfromoneanother.

InLaikipia,predatorsshowedlowerSr/Ca andBa/Ca thantheirprey.IntheNachukui sample,onePanthera specimenfromKalokodo 6wastheonlyterrestrialcarnivoreavailableforanalysis.HerewecomparethePanthera toonespecimenofPapio availablefromKalokodo 6.Majorconclusionscannotbederivedfromasinglecarnivore,yetthelowerSr/Ca andBa/CaratiosofPanthera (carnivore)relativetoPapio(omnivore)isintriguingandwarrantsfurtherresearch.

Site Abbreviation Age(Ma)Lomekwi3 LOM-3 3.4– 3.2Lokalalei1 LA1 2.4– 2.2Lokalalei2C LA2C 2.4– 2.2Nasura1 NAS1 2.3– 2.0Nasura2 NAS2 2.3– 2.0Nasura3 NAS3 2.3– 2.0Kalokodo6 KLD6 1.8– 1.6NaiyenaEngol1 NY1 1.8– 1.6NaiyenaEngol2 NY2 1.8– 1.6Nachukui6 NK6 1.3 – 1.1Nadung’a3 NAD3 0.9 – 0.7

GrazersHipparionKobus

Theropithecus

MixedFeederAepycerotini

GrazerProboscidea

BrowserGiraffa

GrazersHexaprotodon

EquusTragelaphiniAlcelaphiniBovini

GrazersProboscidea

Rhinocerotinae

BrowserBovidae

GrazersHipparionKobus

Theropithecus

MixedFeederAepycerotini

GrazerProboscidea

BrowserGiraffa

GrazersProboscidea

Rhinocerotinae

BrowserBovidae

Pedogenic carbonated13Cvalues(Quinnetal.,2013,unpublished;Harmand etal.,2015)wereusedtocalculatethefractionofwoodycover17throughtimeintheNachukuiFormation.

DespitechangeinthevegetativestructureintheNachukui Formation,therelativeSr/CaandBa/Caratiosamongstfossiltaxadonotvarybysite,implyingthattraceelementsmaybeusefulatgaugingdietarydifferencesamongsttime-transgressivefaunalassemblagesandvegetationcommunitychanges.

SampleCollectionandPretreatment

fromeachspecimenwasweighedandtreatedwith0.5mLof65%HNO3 inTeflonbeakers.Thesolutionwasevaporatedtodrynessonahotplate.Residuewasdissolved,accordingtostandardsofthelab,into5mLof2%HNO3 tobeanalyzed.Twomodernzebrasampleswereanalyzedmultipletimestoserveasaninternalstandardbetweenruns.NISTSRM1400(boneash)wasusedastheexternalstandard.Errorisestimatedas±3%.

RedunciniLM3 fromLA1

AepycerotiniLM3fromLOM-3

Family

Tribe Diet* N δ13Crange

Camelidae

Browser 3 -11.6to-10.2‰

Deinotherioidea Browser** 1 Giraffidae Browser** 1

Felidae Carnivore 1 -4.5‰

Bovidae Bovini

Grazer 3 -0.9to.02‰

Bovidae Tragelaphini

Grazer 3 -1.5to2.4‰

Bovidae Aepycerotini

Grazer(MixedFeeder) 8 -1.6to0.6‰Bovidae Alcelaphini Grazer(MixedFeeder) 8 -4.8to1.6‰

Bovidae Antilopini

Grazer(MixedFeeder) 4 -2.9to0.6‰

Bovidae Reduncini

Grazer(MixedFeeder) 4 -3.8to1.0‰

Bovidae Grazer(Browser) 5 0.0to-8.6‰

Hippopotamidae

Grazer(MixedFeeder) 8 -5.6to-1.2‰Cercopithecoidae Papionini Grazer(Omnivore) 5 -2.1to-1.9‰

Equidae Grazer 4 -0.6to0.2‰

Rhinocerotidae

Grazer 3 -0.9to-0.5‰

Proboscidea Grazer(Browser) 16 -10.1to0.6‰Suidae

Omnivore 10 -2.1to0.1‰

0

100

200

300

400

500 55Mn64Zn66Zn68Zn85Rb87Rb89Y139La147Sm172Yb232Th235U238U

126

356

284

1510

55Mn 64Zn 66Zn 68Zn 85Rb 87Rb 89Y 139La 147Sm 172Yb 232TH 235U 238U

BelowDetectableLimit14.1

Wegaugeddiagenesis intheTurkanafossilenamelsamplesbymeasuringMn,Zn,Rb,Y,La,Sm,Yb,Th,andU.Concentrationsof55Mnand87Rbaresignificantlyhigherinthefossilenamelsamplesthaninthemodernassemblage.WeinterpretthattheTurkanafossilenamelsamplehasundergoneelement-specificdiageneticeffects,butstillholdspromisefortraceselementanalysisforinferringtrophiclevel.

232Th 235U 238U 64Zn 66Zn 68Zn 85Rb 87Rb 55Mn

Modern & Fossil

55MnElement

0

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ModernFossil

Modern & Fossil

55MnElement

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ModernFossil

Modern & Fossil

232Th 235U 238U 64Zn 66Zn 68Zn 85Rb 87RbElement

-50

0

50

100

ModernFossil

Modern

Fossil

Feibel(2011):LocalitymapoftheTurkanaBasin.

FaunalsamplesanalyzedherewereexcavatedbytheWestTurkanaArchaeologicalProjectandarehousedintheArchaeologyDepartmentoftheKenyaNationalMuseumsinNairobi.

Enamelwassampledwithadiamond-tippedrotarytool(ForedomSeries)fromcleansurfacesofwholeteeth.Wepreferentiallysampledlate-formingteethdependingonspeciesknowneruptionsequences.Halfofthesamples(n=45)werepretreatedwith0.1Maceticacidfortenminutesthenrinsedthreetimeswithdistilleddeionizedwater.Nosignificantdifferencesexistbetweenpretreatedorunpretreatedsamples18.

**δ13Cvaluesunavailable

Turkanafossilenamelconcentrations(ppm)

Modern-fossilenamelconcentrationdifferences(ppm)

Results:Sr/Ca andBa/Ca Modern-FossilComparisons

Allreferencesdenotedbysuperscriptnumbersareprovidedonhandout.

One-wayANOVA

One-wayANOVA

Laikipia vs. Nachukui

0.7 0.8 0.9 1.0 1.1 1.2

0.1

0.2

0.3

0.4

0.5

0.6

0.7AntiloEquidRedunTragelLaikipia

Antilopini

Reduncini

Tragelaphini

Ba/Ca

Nachukui

Laikipia

R2=.92

Laikipia vs. Nachukui

2.5 3.0 3.5 4.0

1.0

1.5

2.0

2.5

AntiloEquidRedunTragelLaikipia

Antilopini

Hipparionini/Equini

Reduncini

Tragelaphini

Sr/Ca

Nachukui

Laikipia

R2=.96

WefoundgoodagreementbetweenfossilandmodernSr/Ca(R2=0.96)andBa/Ca(R2=0.92)ratiosoftragelaphini,antilopini,redunciniandhipparionini/equini.

NotablyforBa/Ca,thedistributionofdataprohibitsameaningfulinterpretation.

Next,between1.0-1.5mgofenamelpowder

Ba/Ca

1.00

1.05

1.10

1.15

1.20

1.25

1.30

1.35

1.40

1.45Taxa

Felidae PantheraPapionini Papio

Ba/Ca

PapioniniPapio

FelidaePanthera

Hipparionini/Equini