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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
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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.
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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)
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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
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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
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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 ?
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Mapping and ExcavationMapping and Excavation
StegosaurusAllosaurusOther
Stegosaurus
Allosaurus
Allosaur
Stegosaur
Sauropod and Stegosaur
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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).
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Taphonomic MarkingsTaphonomic Markings
Pathologic DeformationPathologic Deformation--left sideleft side
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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:
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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
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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)
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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
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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.
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