Taphonomy and Rare Earth Element Geochemistry of the Stegosaurus Sp

8/8/2019 Taphonomy and Rare Earth Element Geochemistry of the Stegosaurus Sp

1/26

Taphonomy and Rare EarthTaphonomy and Rare Earth

Element Geochemistry of theElement Geochemistry of theStegosaurus sp.Stegosaurus sp. at the Clevelandat the ClevelandLloyd Dinosaur Quarry, EmeryLloyd Dinosaur Quarry, Emery

County, UtahCounty, Utah

by Celina Suarezby Celina Suarez

Trinity UniversityTrinity University Temple UniversityTemple UniversitySan Antonio, TXSan Antonio, TX Philadelphia, PAPhiladelphia, PA


2/26

Geologic SettingGeologic Setting

Morrison FormationMorrison Formation Brushy Basin MemberBrushy Basin Member

Exposed by the SanExposed by the SanRafael monoclineRafael monocline

Located below variegatedLocated below variegatedbeds of the upper mostbeds of the upper mostBrushy Basin, in a sectionBrushy Basin, in a section

dominated by graydominated by graysiltstones, lacustrinesiltstones, lacustrinelimestones, and smalllimestones, and smallchannel sandstones.channel sandstones.


3/26

The Cleveland Lloyd DinosaurThe Cleveland Lloyd Dinosaur

QuarryQuarry The largest deposit ofThe largest deposit of AllosaurusAllosaurus

fragilisfragilis in the worldin the world 47 (Gates,47 (Gates,2002)2002)

over 10,000 bonesover 10,000 bones Deposited in a calcareousDeposited in a calcareous

mudstone with small concretionsmudstone with small concretionsto large concretionary layers ofto large concretionary layers ofcarbonate, capped by a lacustrinecarbonate, capped by a lacustrinelimestonelimestone

Most recent research: ephemeralMost recent research: ephemeralpond that accumulated bones aspond that accumulated bones asthe result of multiple droughtthe result of multiple droughtevents (Gates, 2002)events (Gates, 2002)


4/26

Taphonomy and Rare Earth Element GeochemistryTaphonomy and Rare Earth Element Geochemistrythethe Stegosaurus spStegosaurus sp. in the CLDQ. in the CLDQ

Is the taphonomic analysis of the Stegosaurs in the research squaresignificantly different than the taphonomic analysis of the Allosaurs?

Is the REE geochemistry of the Stegosaurs significantly different from theAllosaurs?

Does the REE geochemistry analysis support the findings of Gates(2002)?

Population StudyPopulation Study

Various taphonomic approaches to Cleveland Lloyd

Bone positioningBone positioning Taphonomic markings orTaphonomic markings or bone alteration and surface features Lithologic EvidenceLithologic Evidence Rare Earth Element GeochemistryRare Earth Element Geochemistry


5/26

Review collections material => population number ofReview collections material => population number ofStegosaurusStegosaurus

Excavation and Mapping => biostratigraphic positionsExcavation and Mapping => biostratigraphic positionsand orientation of bonesand orientation of bones

Taphonomic Analysis => abrasion, weathering, fracture,Taphonomic Analysis => abrasion, weathering, fracture,surface tracessurface traces

Rare Earth Element Geochemistry => concentrationsRare Earth Element Geochemistry => concentrationsand ratiosand ratios


6/26

Results: Population SurveyResults: Population Survey Minimum of sixMinimum of six

individuals ofindividuals ofStegosaurusStegosaurus based onbased onthe number of humerithe number of humeriand scapulaeand scapulae

Element Type Length UMNHVP UUVP# Comments

Appendicular

HUMERUS R ? 3039 ?

HUMERUS R 40-656 ?

HUMERUS R 40-657 ?

Humerus R 5694 CEUM

Humerus R 450 5271 5696 none

Humerus R ? 3474 LACMHumerus L 450 3809 LACM; CEUM?

Femur R 760 5272 5699

Femur R 770 5274

Femur R 2376 LACM

FEMUR R 40-651 ?

FEMUR R 40-652 ?

Femur L 890 5275 5693

Femur L 5278 broken, condial only?

FEMUR L ? 2375 ?

FEMUR L 4354 ?

Scapula/coraR 5691 CEUM

Scapula/coraR 680 5546a 5690a

Scapula R 580 5483 5689

SCAPULA R 40-653 ?

Scapula/coraR 570 721 broken distally?

Scapula/coraL 870 5276 2561

Scapula L ? 3423 LACM

SCAPULA L 3017 ?

Scapula/coraL 590 5692

SCAPULA L 40-654 ?

Scapula L 660 5277 3017SCAPULA ? ? 2529 ?


7/26

Mapping and ExcavationMapping and Excavation

StegosaurusAllosaurusOther

Stegosaurus

Allosaurus

Allosaur

Stegosaur

Sauropod and Stegosaur


8/26

Bone PositioningBone Positioning

Mostly flat lyingMostly flat lying Some degree ofSome degree of

orientation due toorientation due toseasonal fluvial activityseasonal fluvial activity

Bones in the researchBones in the researchsquare are autochthonoussquare are autochthonousbased on the presence ofbased on the presence oflarge bone material andlarge bone material andsmall sediment size,small sediment size,which is also consistentwhich is also consistentwith findings by Gateswith findings by Gates(2002).(2002).


9/26

Taphonomic MarkingsTaphonomic Markings

Pathologic DeformationPathologic Deformation--left sideleft side


10/26

Taphonomic Markings: FractureTaphonomic Markings: Fracture

Only one:Only one:AllosaurusAllosaurus

gastraliagastralia 30% of bones30% of bones

in the bonesin the bonessurveyed bysurveyed by

Gates (2002)Gates (2002)have fractureshave fractures

No significantNo significanttramplingtrampling


11/26

Taphonomic Analysis: Surface TracesTaphonomic Analysis: Surface Traces Teeth MarksTeeth Marks onlyonly StegosaurusStegosaurus, none on, none on AllosaurusAllosaurus bonesbones

Throughout the quarry, bones of herbivorous dinosaurs contain theThroughout the quarry, bones of herbivorous dinosaurs contain themost teeth marks (Gates, 2002).most teeth marks (Gates, 2002).

Allosaurs preferentially prey upon the herbivorous animals, ratherAllosaurs preferentially prey upon the herbivorous animals, ratherthan scavengethan scavenge


12/26

AbrasionAbrasion AbrasionAbrasion mostly low, and slightly more onmostly low, and slightly more on StegosaurusStegosaurus

bonesbones

Gates (2002), notes prevalence of low level of abrasion onGates (2002), notes prevalence of low level of abrasion oncentra of vertebraecentra of vertebrae

Bias since majority ofBias since majority of StegosaurusStegosaurus material were vertebraematerial were vertebrae Supports some fluvial activity when combined with boneSupports some fluvial activity when combined with bone

orientation dataorientation data


13/26

Taphonomic MarkingsTaphonomic Markings

At least portions of the bones in the quarry wereAt least portions of the bones in the quarry wereexposed because of evidence of scavenging/exposed because of evidence of scavenging/predation.predation. Weathering stages between 0 and 1Weathering stages between 0 and 1 not significantnot significant

exposureexposure

Stegosaurs were more susceptible to predationStegosaurs were more susceptible to predationdue to drought conditions (Gates, 2002).due to drought conditions (Gates, 2002).

Bias of teeth marks on theBias of teeth marks on the StegosaurusStegosaurus bones versusbones versusthethe AllosaurusAllosaurus bonesbones AllosaurusAllosaurus preferred predation rather than scavengingpreferred predation rather than scavenging

since there are less teeth marks onsince there are less teeth marks on AllosaurusAllosaurus bonesbones


14/26

Results: LithologyResults: Lithology Thin SectionsThin Sections

Mostly clays, CaCOMostly clays, CaCO33,,plagioclase, quartz,plagioclase, quartz,some hematitesome hematite

MicrofossilsMicrofossils

ostracodes andostracodes andcharophytescharophytes

MicrofossilsMicrofossils indicativeindicativeof shallow, lowof shallow, low--energyenergywaterwater

1 mm 1mm

1mm


15/26

Rare Earth Element GeochemistryRare Earth Element Geochemistry

LaLa LuLu

During weathering,During weathering,

REE undergoREE undergofractionationfractionation

Aqueous REEAqueous REEsignatures vary withsignatures vary withpH and redoxpH and redoxconditions in differentconditions in differentdepositionaldepositionalenvironmentsenvironments


16/26

Fractionation and REE of Fossil BoneFractionation and REE of Fossil Bone

REE substitute for Ca inREE substitute for Ca in

the biogenic apatitethe biogenic apatitecrystal structure duringcrystal structure duringearly diagenesisearly diagenesis

Bones record the poreBones record the pore--water REE chemistry ofwater REE chemistry ofthe originalthe originaldepositional/diageneticdepositional/diageneticenvironmentenvironment


17/26

REE SignaturesREE Signatures

HREE are associated with alkaline waters (highHREE are associated with alkaline waters (highpH)pH)

LREE are associated with acidic and neutralLREE are associated with acidic and neutralwaters (low pH)waters (low pH)

Alkaline environments include: evaporiticAlkaline environments include: evaporiticlacustrine settingslacustrine settings established lakes with highestablished lakes with highdegree of evaporation, carbonate depositiondegree of evaporation, carbonate deposition

Acid environments include: waterAcid environments include: water--loggedloggedsettings such as swampy areassettings such as swampy areas


18/26

REE Geochemistry Bone Sampling

Cortical bone was collected fromAllosaurus and Stegosaurus bones

excavated from the research square

Cortical bone has a higher concentration

of REE than trabecular bone


19/26

Comparing theComparing the AllosaurusAllosaurus andand StegosaurusStegosaurusbones:bones:

All boneshave similar

signatures (shape)

All bones arefossilized in sameenvironment

Eu anomaly indicatesvolcaniclastic REEsource

Signatures of bones inthe quarry are flatwith a slight depletionof HREE indicating aneutral pH to slightly

acidic environment


20/26

Ternary DiagramTernary Diagram

The ternary diagram is a wayto quantify spider diagram in amore presentable format

Ternary shows relative ratios of Light REE Nd

Middle REE Gd Heavy REE Yb

Points are clustered showingsimilar REE ratios i.e. the samedepositional environment

Supports an autochthonousdeposit of bones also seen intaphonomic evidence


21/26

REEconcentrationsof total data set:

Includes bones fromquarry: mudstone, contact,and capping limestone; pluslimestone ridge to the north

Neutral pH environment

Fluvial activity* orientation* abrasion* rip-up clasts

(Gates, 2002)

Indicate:


22/26

REE Geochemistry: Depositional SettingREE Geochemistry: Depositional Setting

Supports the ephemeral pond settingSupports the ephemeral pond setting

described by Gates (2002).described by Gates (2002). Occasionally to seasonally dries outOccasionally to seasonally dries out

Flooding/ or wet season refreshed the pondFlooding/ or wet season refreshed the pondwith neutral pH giving flat REE signatures,with neutral pH giving flat REE signatures,

and orienting the bonesand orienting the bones Neutral pH pond area, not established lakeNeutral pH pond area, not established lake


23/26

ConclusionsConclusions

Six Stegosaurs are currently found at the CLDQ. One Stegosaur isSix Stegosaurs are currently found at the CLDQ. One Stegosaur isrepresented in the study area.represented in the study area.

All the bones in the quarry were fossilized in the same depositionalAll the bones in the quarry were fossilized in the same depositionalenvironment, supporting an autochthonous accumulation.environment, supporting an autochthonous accumulation.

The depositional environment of Cleveland Lloyd was a neutral pHThe depositional environment of Cleveland Lloyd was a neutral pHenvironmentenvironment Ephemeral pondEphemeral pond Some fluvial action due to oriented and slight abrasion of bonesSome fluvial action due to oriented and slight abrasion of bones

and enough sediment supply to depress the formation of onlyand enough sediment supply to depress the formation of onlylimestone, and give flat REE signatureslimestone, and give flat REE signatures

Not enough water to support aquatic fauna or significant plantsNot enough water to support aquatic fauna or significant plants Microfossils support shallow water environmentMicrofossils support shallow water environment

These occasional to seasonal variations supported byThese occasional to seasonal variations supported bypaleoenvironmental interpretations of the Morrison Formation aspaleoenvironmental interpretations of the Morrison Formation asbeing highly seasonal by Dodsonbeing highly seasonal by Dodson et al.et al. (1980)(1980)


24/26

AcknowledgementsAcknowledgements Temple UniversityTemple University: Dr. David E. Grandstaff and Dr.: Dr. David E. Grandstaff and Dr.

Dennis O. Terry Jr.Dennis O. Terry Jr. Trinity UniversityTrinity University: Dr. Edward C. Roy Jr.: Dr. Edward C. Roy Jr. Univ. of UtahUniv. of Utah: Dr. Scott Sampson, Bucky Gates, Lindsay: Dr. Scott Sampson, Bucky Gates, Lindsay

ZannoZanno Utah Museum of Natural HistoryUtah Museum of Natural History: Mike Getty, Monica: Mike Getty, Monica

Castro, Joe Gentry, Jerry GoldenCastro, Joe Gentry, Jerry Golden BLMBLM Price Field OfficePrice Field Office: Mike Leschin, Frank Davis,: Mike Leschin, Frank Davis,

Sam Espinoza, Elsa LangraneSam Espinoza, Elsa Langrane Univ. of PennsylvaniaUniv. of Pennsylvania: Dr. Peter Dodson and his: Dr. Peter Dodson and his

Evolution of Dinosaurs classEvolution of Dinosaurs class

Doreena PatrickDoreena Patrick Dr. Clive TruemanDr. Clive Trueman Financial SupportFinancial Support: Trinity University, Tinker Family,: Trinity University, Tinker Family,

GSA SouthGSA South--Central Undergraduate Research GrantCentral Undergraduate Research GrantProgram, Bureau of Land ManagementProgram, Bureau of Land Management

Marina Suarez, and all friends, family, and reviewersMarina Suarez, and all friends, family, and reviewers


25/26

ReferencesReferences

Dodson, P., Behrensmeyer, A.K., Bakker, R.T., and McIntosh, J.S., 1980, TaphonomyDodson, P., Behrensmeyer, A.K., Bakker, R.T., and McIntosh, J.S., 1980, Taphonomyand Paleoecology of the dinosaur beds of the Jurassic Morrison Formation:and Paleoecology of the dinosaur beds of the Jurassic Morrison Formation:Paleobiology, v. 6, no. 2, p. 208Paleobiology, v. 6, no. 2, p. 208 232.232.

Gates, T.A., 2002, The Cleveland Lloyd Dinosaur Quarry as aGates, T.A., 2002, The Cleveland Lloyd Dinosaur Quarry as adroughtdrought--induced assemblage: late Jurassic Morrison Formation,induced assemblage: late Jurassic Morrison Formation,

central Utah [Master of Science Thesis]: Salt Lake City, Utahcentral Utah [Master of Science Thesis]: Salt Lake City, Utah University ofUniversity ofUtah, 57p.Utah, 57p.

Trueman, C.N., 1999, Rare earth element geochemistry and taphonomy of vertebrateTrueman, C.N., 1999, Rare earth element geochemistry and taphonomy of vertebrateassemblages: Palaios, v. 14, p. 555assemblages: Palaios, v. 14, p. 555--558.558.

Trueman, C.N. and Tuross, N., 2002, Trace elements in recent and fossil boneTrueman, C.N. and Tuross, N., 2002, Trace elements in recent and fossil boneapatite,apatite, inin Kohn, M.J., Rakovan, J.F., Hughes J.M., eds., Reviews inKohn, M.J., Rakovan, J.F., Hughes J.M., eds., Reviews inmineralogy and geochemistry: Phospates: geochemical, geobiological, andmineralogy and geochemistry: Phospates: geochemical, geobiological, andmaterials: Washington D.C.:The Mineralogical Society of America, v. 48, p.materials: Washington D.C.:The Mineralogical Society of America, v. 48, p.489489--521.521.


26/26

Taphonomy and Rare Earth Element Geochemistry of the Stegosaurus Sp

Documents

Transcript of Taphonomy and Rare Earth Element Geochemistry of the Stegosaurus Sp