This document analyzes evidence for whether T-Rex was a predator or scavenger. It examines T-Rex teeth shape, size, and serrations, finding they were adapted for bone crushing, not slicing meat, indicating scavenging. Tooth marks on bones also suggest scavenging, as marks are often in odd areas a predator wouldn't access first. While one find showed T-Rex bite marks on a living animal's spine, this is rare evidence, and different scenarios could also explain it, so the document concludes the evidence overall supports T-Rex being a scavenger rather than a predator.

1. 1
Was T.rex The King of the Dinosaurs
By Cara Patel
HeathfieldSchool
Centre Number:12728
Candidate Number: 3680

2. 2
Contents
Introduction.................................................................................................................................3
Teeth and Jaws............................................................................................................................. 4
Shape:......................................................................................................................................4
Teeth Marks on Bones:.............................................................................................................. 5
Big Brain......................................................................................................................................7
Arms............................................................................................................................................ 9
Strength...................................................................................................................................9
Protection................................................................................................................................ 9
Leg Bones and Speed.................................................................................................................. 11
Modern Fast Animals:............................................................................................................. 11
Studies Done To Estimate T.rex Speed...................................................................................... 11
My Own Study........................................................................................................................ 13
Prediction:.......................................................................................................................... 14
Data: .................................................................................................................................. 14
Graph:................................................................................................................................ 15
Statistical Analysis:.................................................................................................................. 15
Evaluation:............................................................................................................................. 15
Conclusion:............................................................................................................................. 16
Miscellaneous ............................................................................................................................ 17
Tyrannosaurus Sue.................................................................................................................. 17
Ecosystem.............................................................................................................................. 17
Conclusion ................................................................................................................................. 18
Appendix 1 – Statistical Analysis.................................................................................................. 19

3. 3
Introduction
The TyrannosaurusRex (T.rex) wasfirstdiscoveredbyBarnumBrownin1902 (despite the
mix updescribedbyJack Horneras “He didn’trealise that...T.rex hadalreadybeendiscovered,
twice,one of those timesbyhimself” i
). Archaeologistsandscientistsassumedthatitwasa
fearsome predator.Justata glance,featureslike the massive jaw withserratedteethandsharp
clawsleadto thisconclusion.
HenryOsbornnamedthe skeleton thatBarnumBrown had excavatedTyrannosaurusRex
meaning“TyrantLizard King”inLatin.There have beenseveral variationsof this:“The Kingof the
Dinosaurs”i
, “The King”ii
, “DinosaurKing”iii
and“King Lizard”iv
.
The T.rex is the most famousdinosaurknowntomanwithitsappearance infilms i.e.,“King
Kong”,“The Land Before Time”,“KingDinosaurs”and“JurassicPark”,inbooksand eveninthe
theatre – “WalkingWithDinosaurs,The ArenaSpectacular”at WembleyArena.
To earn the title of “The Kingof the Dinosaurs”,the T.rex wouldhave hadtohave beena
successful hunterandadeadlykiller.Inthe presentday,there are manyaspectsthatmake a
successful predatorthe mostimportantbeingameansof killingprey,suchas,claws/sharp
teeth/tool etc.Some animalsrushatpreywitha burstof speed,likethe cheetah,some layinthe
shadowsbefore pouncing, suchas,snakesandothers use camouflage tosurprise theirprey,i.e.,the
great white shark withawhite bellytoblendinwiththe waterwhenpreylookupanda dark back to
blendinwiththe waterwhenpreylookdown.
Recently several scientists have startedtochallenge the ideaof the T.rex beingapredator.
In thispaperI aimto examine the evidence lookingatthe differentpartsof the T.rex’spredatory
weaponry separatelyincludingteeth,arms,legs,speedandbrain,andcome to myown conclusions.

4. 4
Teeth and Jaws
Shape:
Whenthe firstT.rex skeletonwasfound,the archaeologistssaw thatthe teethwere sharp
and assumedthatthe T.rex was a predator.Thisview wassharedbythe scientistswhostudied the
fossil.However,since that time,scientistshave realisedthathow sharpa tooth’sedge is,isnotthe
onlyfactor affectingthe positionof ananimal onthe foodchain.Evenin prehistoricanimals,there is
a huge range in variationof toothsize andshape withinthe carnivoreseachhavinganindividual
function.
As a predator,the T.rex would have neededthin,dagger-like teethsimilartothose foundon
contemporarypredatorydinosaurssuchasVelociraptor, asthe killerstendtogetthe bestof the kill
i.e., the muscle andorgans. KevinPadien –anEvolutionaryBiologistof the PadienLabatthe
Universityof Californiadescribethe teethof the T.rex asbeing“like lethal bananas”v
. Shorter
sturdierteethwouldhave still packedalethal punchwiththe powerof the T.rex’sbite whichwas
“eighttimesaspowerful asa lion’s”vi
.Such a powerful bite wascausedby“wide cheeksanddeep
jawssupportedbigger,more powerful jaw musclesthanthose of anyotherdinosaurwe know”says
Jack Horneri
. Horner– the curator of palaeontologyatMontanaState University – thinksthatthe
reasonfor thisisthat the teethwere notdesignedforslicingbutforbone crushing.If the T.rex had
beena scavenger,thickteethwouldhave beenuseful aswhatwouldbe leftof acarcass whena
predatorhad finishedwithitwouldbe the bonesandgristle.
Some scientistsinsistthatthe teethwere large forsucha large carnivore.However,research
done byJim Farlow – a palaeontologistatthe Indiana-Purdue University –contradictsthisbelief.
Lookinginto the proportionsbetweenthe size of the teethtothe size of the T.rex,he foundthat“its
teethwere oversized”i
.
T.rex’steethare alsoserrated.Some scientistsforexample PhilCurrie –a museumcurator
and a professoratthe Universityof Alberta,Canada,say thatthe serratedteethare “beautifully
adaptedto sawbone and meat”i
. There is a general agreementwiththisview asdemonstratedby
the fact that The Natural HistoryMuseumsay“theirdagger-like shapeandserratededgeswere
designedtokill,slashandtear”.Anotheridea(proposedbyBill Abler – a researcherof dinosaur
toothstructure in Chicago) isthat the serrationsprovidedahome forbacterial coloniesinwere if
pray wasbitten,the bacteriawouldweakenorkill the victim.Howeverthisview haslittle evidence
to supportit.It is unlikelythatbacteriacouldhave survivedcontinual chewingandthere are toofew
livinganimalsthathave serratedteethtomake aclear comparison(KomodoDragonandSharks).
Some scientists’ideascontradictthe view of the serrationsbeinguseful forhunting,one
example beingJimFarlow whothinksthatthe serrationsallowedthe T.rex toget“a bettergripon
the victim”i
.
From thisevidence Iconclude thatthe shape andsize of the T.rex’steethindicatesthatthe
T.rex was indeedascavengerasthe bone crushingpowerwouldnothave beenneededif itwasa
predatoreatingthe bestparts of a kill.

5. 5
Teeth Marks on Bones:
Until now,teethmarksleftonthe bonesof dinosaurswere a useful tool inthe identification
of the positionof animalsinthe foodweb.Once the animal wasidentifiedfromthe teethmarks,if
vaguelyresemblingapredator,itwas assumedthatitwas responsible forkillingthe prey.However,
inthe case of the T.rex,newevidence andre-examinationof oldevidence suggests differently.
An online article says“boneshave beenfoundwithtyrannosaurusembeddedinthemor
scratchedby them,butso far no studyhas shownthattyrannosauruskilledotherdinosaursfor
food”v. There have beenagrowingnumberof caseswhere the teethmarksof the T.rex have been
foundonthe bonesof otherdinosaursand,fromperspectiveof the T.rex beingapredator,the facts
don’tadd up.
One interestingexample documentedinDinosaursbyDougal Dixon isof a Triceratopspelvic
bone,which raisestwoissues.The firstbeingthatthe scrape marks are onthe underside of the
bone,“fromthese marks,scientistscouldtell thatatyrannosaurusbitdown...whenthe triceratops
was alreadydead”vii
.Thisleadsontothe nextissue whichisthat,fora predator,to gofor the pelvis
of a carcass is an oddityinitself.Whenaprayanimal iskilledinthe presentday,the predatorthat
killsitnormallyhasfirstpickat the carcass. Thisis unlessalargerpredatorscares awaythe firstfrom
the carcass or ina packenvironmentwhere superiorseatfirst.Predators typicallystartwith areas
that are predominantlymuscleforexample the underbellyorthighleavingscavengerstoscrape
scraps off bones.Itishighlylikelythatancientanimalsalso exhibitedthe same behaviour.Asa
predatorit wouldnotbe expected forthe T.rex bone markstobe lefton the underside of the pelvis;
thisonlymakesitmore likelyforthe T.rex tohave beena scavenger.
There has beenone findof a preyanimal with T.rex bite marksonthe spine,whichmany
believeprovesthatthe T.rex wasa predator.Anarticle documentingthisfindsays“becausethis
injuryshowssubsequentre-growthof bone,thiswoundwasinflictedonalivinganimal ratherthana
carcass”viii
. One conclusiontodraw isthat the T.rex was indeeda predator, howeverasthisisa rare
find,differentscenariosmust be considered.There have beenskeletonsof preyanimalswhere they
have beencaughtby more than one carnivore anddue to external factorswere able toescape.One
example isshownonaBBC documentary – “PlanetDinosaur”.InNorthAfrica90 millionyears ago,a
juvenileParalititangotcaughtina “deadlygame of tug of war”ix
saysJohnHurst (narrator) between
a Sarcosuchusand a Carcharodontosaurus.There were toothmarksonthe neck andhindlegfrom
the two differentpredatorswhichshowedbone re-growth.Sarcosuchuswasan8 toncrocodilian.
Howeverbeingnomatchfor the 6-15 ton Carcharodontosaurus,itstooddown.Itisbelievedthatthe
babyParalititanwasable toescape as membersof the heardmovedinto protectit.Despite being
one of the more fearsome predatorsinNorthAfrica,anadultCarcharodontosauruswouldneverpick
a fightwitha herdof 60 ton Paralititansandthe babywasable to escape.
In termsof the T.rex,evenanobligate scavengerwouldnotmissupanopportunitytotake
advantage of anotherpredator’shunt.JackHorner says“T.rex was simplythe greatestopportunist
of themall”i
.Despite the attackinNorthAfricainvolvingdifferentdinosaursatadifferenttime I
believetheycanbe comparedas to finda bite markfroma T.rex showingsubsequentbone re-
growthis sucha rare event whencomparedtothe numberof fossilsfoundwithT.rex bite marks.It
isa possibilitythatthe T.rex tookadvantage of a predator’shuntandgot a holdon the preybut due
to otherfactors itwas able toescape.

6. 6
In conclusion,Ibelievethatthisevidence stronglysupportsthe T.rex beingascavengerdue
to the proportionof bite marksfoundbeingwhenananimal wasalreadydead.

7. 7
Big Brain
It issaid that“carnivorousdinosaurshadthe biggestbrainsfortheirbodysize”x
.“They
neededsuchbigbrains,togetherwithkeensensestotrackdowntheirprey”x
says Firth.However
makingassumptionsonthe sensesof adinosaurbysimplylookingatthe overall brainsize doesnot
provide anyinformationaboutthe individual senses.Todo this,scientistshave foundwaysto
measure the braincavityand to create computergeneratedimagesof the brain.
Withtoday’stechnology,aT.rex skull canbe put througha CAT scan where highquality
imagesandin-depthanalysiscanbe carriedout.It is a preferable methodasthe skull isnot
damagedbutthisis costlyas no hospital CATscannerinthe worldislarge enoughto fitsucha
mammothhead.However,inAmericathere hasbeenone builtthatislarge enough andthroughthis
newlighthasbeen shedonthe brain cast of T.rex.
Before the CATscanner,the onlymethodtoanalyse the braincavity was byeye.Fromdata
collected byvisual examination,scientistsbelievedthatthe T.rex possessedan acute sense of smell
and average eyesightwiththe possibilityof depthperception“it’slikelythatT.rex hadsuperior
eyesightforadinosaur”i
.By lookingatthe braincavityestimatescouldbe made onthe proportion
of differentsectionsof the brain.Fromthese estimatesitwasfoundthatthe opticlobeswere of
moderate size whereas“Tyrannosaurushadverylarge olfactorylobes(theareainthe brainusedfor
processingodours)”saysHenryF. Osbornxi
.
Basedon these estimates,scientistsdrew togethertheoriesaboutthe eyesightof
Tyrannosaurus.“T.rex hada narrow eye socket” i
saysJack Horner whichhe believedcouldhave
produceda sharperimage while forwardfacingeyescausedthe beliefthatthe image receivedby
each eye overlappedandcreatedthe possibilityof judgingdistances.Thiswouldbe anextremely
useful tool inhunting andprovide anadvantage overotherpredators.
It was seenthat“there were alsomanyholesfornervesinthe snoutof the T.rex”i
.This
coupledwithenlargedolfactorylobescreatedthe potential foranimmense sense of smell,which
wouldbe advantageous tobothpredators(trackingprey) andscavengers - “a keensense of smell
wouldhelpfindrottingmeat”i
.
Withthe recentCATscan data, exactvaluesratherthanestimateshave beenpossible.The
firstimagesof the T.rex brainwere showntobe wrongby Lawrence M. Witmerand RyanC. Ridgely
whofoundthat a “portionof the olfactoryregionof the nasal cavityisthe sightof sensory
epithelium”xii
.The revisedimageof abraincast shownonthe nextpage withthe relative positions
and sizesof the olfactoryandopticlobeslabelledshowingthatevenwiththe reductionfromoriginal
estimatesof the olfactorylobesare still large.Fromthis,scientistsare now forcedtoadmitthat the
T.rex had “small,weak,beadyeyes”xiii
.
The brain cast was comparedtothat of a scavenger(vulture)andthe T.rex brainwas
proportionallysimilartothatof a vulturexiv
.JackHornercallsit “the vulture of itsday”i
.
The newCAT scan data suggeststhatTyrannosaurus possessedakeensenseof smell and
onlyaverage eyesightithasbeenshowninthe modernscavengingspeciesthatsmellwasmore
importantthaneyesight.The mostrecentevidence suggeststhe T.rex wasmore likelytohave been
a scavenger.

8. 8
Cast of the T.rex Brain
Optic Lobe
Olfactory Lobe

9. 9
Arms
Strength
It was originallythoughtthatthe armsof the T.rex were unnecessaryforsurvival andsoover
time became smallerandweak.Scientistsare now startingtothinkdifferently,the only questionleft
unanswerediswhy?
“The arm bonesare onlythree feetlong”i
whichisaboutthe same as the arm lengthof the
average adulthumanbut ona thirteenmeterlonganimal;“inevolutionit’sanamazingreduction
overearliertyrannosaurs”i
saysJackHorner.
There isa dentleftwhere musclesattachtobone and fromthe depth,lengthandshape,an
accurate approximationof the size of the muscle can be derived.ScientistsMattSmithandKen
Carpenterusedthistechniquetoreconstructthe muscle andtendonsof the T.rex.If it is to be
assumedthatthe T.rex had little armstrength,the scars wouldbe shallow andsmall,however“the
arm boneshave verydistinctmuscle scars”i
.Itwas foundthatalthoughflexibilitywasnotsomething
that Tyrannosauruscouldboastof,itsstrengthwas immense. Whereasourbicepsare around2
inchesindiameter,the T.rex’swere6inches.Thisallowed the T.rex to“hoistfourhundredpounds
towardsitsbody at one time”i
: the same as an adult male lion.
Palaeontologistshave beenunable toidentifyapurpose forthisstrengthasthe arms could
not reachits mouth,theycouldnothelpinfeeding.Somesuggestthattheycouldbe usedincombat
but inclose quarterswithanotherdinosaur,the teethwouldbe amore useful weapon.Tony
GibbonsandRobertShedelonsay“Itispossible thattheywere usedtolifttyrannosaursupfrom
restingposition”xv
whichisareasonable assumptionasthe animal weighed4.5-6tonnes.However
due to the length,there isa limittohowmuch the arms couldhelp.
Thisevidence supportsboththe predatorandscavengertheories untilamore reliable
argumentisput forward.
Protection
In humans,ourarms protectus whenwe fall over.Reflexesmeanthatwe raise ourarms as
we fall sothat our headis protected.Iconductedanexperimenttotestthisbygettingsomeone to
pushme over.AlthoughnotacompletelyfairtestasIwas expectingit,topushan unsuspecting
victimoverwithoutwarningorconsentwouldnothave beenpossible forethicalreasons.
Shownonthe nextpage isa freeze frame fromthe videotaken.

10. 10
A seenabove,Iraisedmyarms so thatmy headdidnot hitthe ground.
To do thiswouldbe impossible forthe T.rex asthe arms were sosmall.“Dropa skull from
that heightandthere’sachance of causinga nastyinjury,evenafatal one”i
says JackHorner. Thisis
more likelytobe takenintoaccountif the T.rex isconsideredapredator.To be runningat topspeed
and to fall overwouldcause more damage thana scavenger, notneedingtorely onspeed.Evenif it
didsurvive sucha fall,itisunlikelytosurviveforverylong.Opentoinfectionandpossiblyunable to
eat,there wouldbe verygrimprospectsforthisTyrannosaur.
I believeitssmall armssuggestthe T.rex was a scavengerandevenif the T.rex wascapable
of greatspeed (asI discussinthe nextsection),todosowouldhave beentoomuchof a risk if it
were tofall over.

11. 11
Leg Bones and Speed
One of the mostimportantattributesof predatorsthroughouthistoryisspeed.Mostif not
all methodsof predationrequire the predatoryanimal tohave ahighspeed;ambushpredation,the
use of poisonortrackingpreyover longdistancesall require preytobe firstcaught.AsGregory
S.Paul says,“there are no slowpredators”(Limbdesign,functionandrunning…).
HenryOsbornwas of the opinionthatthe “tyrannosauruswasunquestionablyfleetof foot”
(the complete T.rex) aviewthatwasheldbyThe New York Timesthatadvertisedthe findcallingita
“swifttwo-footedtyrant”.
Modern Fast Animals:
P. DavidPollyconductedastudyinwhichhe comparedmanymodernanimalscomparing
theircategoryand theirspeed.He foundthatthe graviportal animals(animalswithlarge bodymass)
were the lowspeedanimalsasopposed tothe cursorial animals(fastrunninganimals)xvi
.
The fastestlandmammal isthe cheetahwhichhasmanyadaptationsenablingittoreach
maximumspeedsof 70-75 mph.Whenlookingatthese adaptations,itisseenthatsome are shared
withthe T.rex and some aren’t.
Both the T.rex and the cheetahhave “longlegs”xvii
forpropulsionand“rigidpaws”xvii
- or feet
inthe case of the T.rex - fortraction.They bothhave a longtail (inthe cheetah,“the tail adds60-84
extracm to the length”xvii
).Itis alsoindicatedbyfossilsthatthe T.rex hadlarge lungsandnostrils,a
trait sharedwiththe cheetah. If the T.rex wasa scavenger,eachof these characteristicscouldbe
useful if usedfordifferentfunctions.Longlegsandrigidfeetwouldbe useful fordistance walking,
longtail wouldcounterbalance the T.rex’slarge headandlarge nostrilswouldallow forbetter
detectionof the smell of acarcass from a furtherdistance.
There are manytraitsthat the cheetahhasthat the T.rex lacks.The cheetahhas a “flexible
spine:actingas a spring”xvii
while hittinghighspeeds.The T.rex hadaveryrigidspine tothe extent
that simplymaintainingthe uprightpositionwouldcause possible“dislocationof several joints,
includingthe articulationbetweenthe headandthe spinal column”xviii
.The cheetahis“small witha
slenderstreamlinebody”whilethe T.rex weighing6-8tonnes,wasnot.
One of the mostnoticeable differencesisthatthe cheetahhasa “small aerodynamic
head”xvii
whichisextremelydifferenttothe T.rex where Lawrence WitmerandRianRidgelyclaim
that theirestimate of the weightof the T.rex headof 515.5kgxix
isthe most accurate to date.Thisis
more than the weightof a pregnantpolarbear.
Simplycomparingtraitsof the twospecies,thisindicatesthatthe abilityof the T.rex toreach
highspeedsishighlyunlikely.
Studies Done To Estimate T.rex Speed
There have beenmany experimentsconductedandestimatesof speedfor the T.rex
calculatedhave been overahuge range.For example,BobBakkerestimatesthe T.rex tohave
reachedspeedsof 40-42 mphwhile JimFarlow arguesthatitcouldonlyreach a maximumspeedof
25mph. Some scientistseveninsistthatthe topspeedwasmerely10 mphxiii
. Each testlooksat a
differentaspectof the Tyrannosauruslegfunctionsandbasesspeedassumptionsfromthis.

12. 12
Some of the studiesconductedlookatthe structure andshape of the actual legbones.Jack
Hornerand Don Lesson lookat the thicknessof the legbonescomparedwithsmallerpredators.
Theysaidthat “T.rex’sboneswere farstouterthanthose of mid-sizedpredators…designedto
compensate forthe stressassociatedwithfastrunning”i
.Howevertheythenmake referenceto
several otherstudiesdoneaboutT.rex speedandsaythatno definite conclusioncouldcome from
thisdata.
Studiesof the boneshave alsorevealedextensivemuscle scarring.The evidence forthe
T.rex havinga considerable massof legmuscle supportsboththe scavengerandpredatorargument
as “if it were a scavenger,itwouldhave hadtoroam around lookingforcarrion.If it were ahunter,
it wouldhave hadto track downpray”i
. The extensive legmuscleisalsowhatfuelledthe ideathat
the T.rex stoodup on itshindlegs:“Tyrannosaurusranuprighton itspowerful hindlegs”xx
.
GregoryS. Paul alsolookedatthe structure of the legbones,hismainfocusbeingonthe
flexibilityof the jointsasthe size of the animal increasedlookingatthe T.rex comparedto several
otherspeciessome beingfastrunnersandsome slow.Hismainargumentwasthat“animals
designedinasimilar, mannerfunctionandperforminasimilarmanner”xxi
.Fromlookingatthe
flexibilityof the ankle bonesinparticular,he foundthat“theymaintainedremarkablyuniform,
flexedjointedlimbssuitedforrunningathighspeeds”xxi
.He estimatedthatthe T.rex couldhave
reachedspeedsof 37 mph.This isassumingthatstructuresthat are the same are usedinthe same
wayin differentorganisms.Anexamplewhere thisisnotthe case isdescribedbyR.McNeill
Alexanderwhere he says“Hummingbirdshover,vulturescannot.Vulturessoarandhummingbirds
do not”xxii
.Atthe time the paperby GregoryS. Paul waswritten(1998), he admitsthat “a
comprehensive scalingstudyhasnotbeenperformed”xxi
whichmightprovide agreaterdegree of
accuracy into thisdebate.
Since then,manyscalingmodelshave beendone.One of the mostrecentmodelswasdone
by a US team wholookedatthe most up to date estimatesof T.rex weightandusedthistofind
flexibilitywhile runningatspeeds.Despite some scientistsputtingforwardthe ideathatthe T.rex
couldhave weighed3-4tonnes,theysaythatthe mostrecentestimatesshow that6-8 tonneswould
be a more accurate measurement.Predatorsalsoneedtopossess the ability toturnquicklyduring
huntingtobe able toout-manoeuvre preyandavoiddangers asisthe case formodernpredators.
However,the resultsfromthisteststate the opposite withregardstothe T.rex.Theyclaimthat
tyrannosaurus“hardlyreached25 mph andrequiredacouple of secondsto turn45o
”xxiii
indicating
that chasingand huntingitsprey toobtainfoodwouldbe unlikelyif notimpossible.
Othermodelshave beencreatedbyusingacombinationof scalingandmuscle mass.JohnR.
HutchinsonandMarlano Garcla constructeda model thatestimatedthe massof extensormuscle
requiredinthe legsrequiredforrunning.The modelspredictedthat“inorderto be a goodrunnerit
required80%of itsweighttobe initslegmuscles,whichisnexttoimpossible”xxiv
.The resultsfrom
thisstudyindicate thatthe T.rex could have neverreachedhighspeeds.Thisstudyconcludedthata
T.rex runningat 11-20 m/s wouldhave “beennearorabove itsmaximummuscularcapacity”xxv
.
A similarmodel wasdone byanotherteambyscalingupmodernanimalstoT.rex size.The
testtheyconductedwasto see whatproportionof the overall weightof the T.rex wouldneedtobe
inits legstobe able torun. Theyusedthe chickenas birdsare the dinosaurs’closestlivingrelatives
and a chickenwalksonitstwo hindlegs.Theirresearchshowedthatalthough“achickencouldrun

13. 13
withonlyabout9% of itsmass initslegs”xxvi
as a minimum(mosthavingapproximately11-15%),“a
tyrannosaurussizedchickenwouldneedanimpossible 99% of itsbody mass ineach legto run”xxvi
.
Calculationsof speedhave alsobeendrawnfromfossiliseddinosaurtracks.AdamHibbert
says“study of fossil foot printssuggeststhatT.rex walkedatabouthumanspeed”iv
andfrom this,
scientiststhenscaledupspeedsof running.Howeversome scientists,for example JackHorneri
,
remainsceptical aboutconclusionsdrawnfromfossilisedtracksforseveral reasons:
 It ishard to positivelyidentifythe speciesthatleftthe footprints.
 Footprintsare onlyfossilisedif theyare made inareasof softground.If thisis so,the
animal wouldnotbe travellingattopspeedonsuchterrain.
 Runningat full speed,thereisalarge distance betweeneachfootprint,DavidBurnie
saying“ittook pacesnearly5m long”xxvii
.It ispossible thatonlyafew footprintswere
made on groundsuitable forthemtobe fossilised.
 More than one individual of the same speciesmayhave walkedthe same pathwayor
the same individual repeatedlyusingthe pathwaywhichmaydistortasingle track.
Othertestshave includedagroupthat conductedteststo measure the distance nerve
impulsescouldtravel inagiventime. Fromtheircalculations,nerve impulsestravelledata “basic
speedlimitof 180 feetpersecond”xxviii
.Calculatingthe time itwouldtake fornerve impulsesina
T.rex to travel fromthe foot,up the legand alongthe spinal cordto the brain,theyfoundthat if a
T.rex were toinjure itsfoot,thenitwouldnotrealise ituntil several secondsafterwardswhereit
couldpotentiallydoirreversible damage while continuingtorun.Duringthe study,the T.rex is
comparedto the elephantwhichtheystate “can’truntoo fastor they’re effectivelyrunning
blind”xxviii
.The studyconcludedthat“the mightyTyrannosaurusRex wasnoquick,agile killing
machine … itwouldhave neededtomove slowlytofeel withitsfeet”xxviii
.The testdoesnothowever
suggestthathigherspeedsinT.rex were impossible.
Some scientistsnowbelieve thatdinosaurswereevolvingbeyondthe limitsof modern
reptilesandbecomingwarmblooded.Fossil evidence suggeststhat“T.rex hadlittle internal body
temperature variation”i
.Althoughthe abilitytoregulate bodytemperatureisconsideredatraitof
animalswithhighmetabolicactivity,“itdoesnotmeanthatT.rex was a fastrunner”i
.
There isa range of different estimatesforT.rex butthe evidence suggeststhatitwassimply
too slowandinflexible tocatchprey.
My Own Study
I decidedtoconductmy ownstudyand to make my ownestimate onthe speedof the T.rex.
It isthoughtthat fasteranimalshave a longertibiacomparedtotheirfemur.Iplottedascatter
graph of the ratioof TibiaoverFemurto speedof modernanimalstotestfora correlationandthen
plottedthe T.rex withregardstothe bone ratiosto estimate the speed.

14. 14
Prediction:
The ratios were determined by calculatingthe tibialengthoverthe femurlength.Assuming
that fasteranimalshave alongertibia,sloweranimalshave aratio of <1 and fasteranimalshave a
ratioof >1.
Data:
* lengthsof the legbonesof the T.rex were fromthe documentary“Valleyof the T.rex”xiv
.
** takenfromthe paper “limbdesignsandfunctions...”xxi
.(Allothermeasurementsweremade by
me usingthe bonesat HeathfieldSchool andRoehamptonUniversity)
***(calculatedas assumedtobe 60% of a race horse)
For sourcesof average speeds,refertobibliography.
Species Femur/mm Tibia/mm Ratio(Tibia/Femur) Average
Speed/mph
T.rex* 1270.0 1168.4 0.92 ?
Race Horse** - - 0.88 42.50
Rhino** - - 0.65 15.53
Elephant** - - 0.55 25.00
Human 441.0 340.0 0.77 22.00
Rabbit 105.0 105.0 1.00 35.00
Pony 275.0 380.0 1.38 25.50 ***
Sheep 200.0 120.0 0.60 25.00
Giant Anteater 230.0 204.0 0.87 31.00
Platypus 38.0 67.0 1.76 22.00
White Ruffed Lemur 145.0 132.0 0.91 12.00
RhesusMacaque 147.0 130.0 0.88 35.00
StripedSkunk 61.0 62.0 1.02 10.00
Mara (inthe rodentfamily) 120.0 149.0 1.24 10.00
Rat 29.5 32.9 1.12 8.00
Cat 110.1 113.7 1.03 30.00
Gibbon 209.0 184.0 0.88 35.00
Chimp 288.0 250.0 0.87 25.00
Wallaby 124.9 130.0 1.04 30.00
Small Antelope 125.0 130.0 1.04 43.00
Penguin 78.7 72.3 0.92 2.05 (on land)
Pig 234.0 206.0 0.88 11.00
Ostrich 280.0 500.0 1.79 40.00

15. 15
Graph:
Figure 1: Scatter Graph Showing Animal Speed /mph Plotted Against Bone Ratio
Statistical Analysis:
(See Appendix 1)
Regressionlineequation y= a + bx
a = 19.25269 b = 11.99857
y = 19.25269 + 11.99857x
whenx = 0.92
y = 30.29
Estimated Speed:30.29mph
Evaluation:
The data is lessaccurate than if the average bone lengthsforeachspecieswere usedbutas
thisinformationwasnotavailable,itisassumedthatthe ratiosare the same.My sample size was
small decreasingthe accuracyof my resultshowever the accuracyof the bone lengthswasto a tenth
of a mm.
10
15
20
25
30
35
40
45
0.5 0.75 1 1.25 1.5 1.75 2
AnimalSpeed/mph
Bone Ratio
Linear (Animal Speed /mph)RegressionLine

16. 16
Conclusion:
The top speedof a Triceratopsisestimatedat35mph. Frommy calculationsaT.rex could
not outruna Triceratops at top speed. A T.rex didnothave the speedor the manoeuvrability needed
to take downpreyand therefore itismore likelytohave beenascavenger.

17. 17
Miscellaneous
Tyrannosaurus Sue
Sue was the name giventothe T.rex foundby Sue HendricksoninSouthDakota.The
skeletonisparticularlyimportantbecauseitisover90% completei
butwhatintriguedscientistswas
hersheersize – “Sue’sthighbone (femur) measuresfifty-fourincheslong”i
.Few dinosaursreached
oldage because of the dangerstheyfacedona dailybasis.
Sue sustainedseveralinjuriesthroughoutherlifewhichshowedre-growthof bone,one of
these injuriesbeingof particularimportance.Sue hadbrokenfootboneswhichweremostlikely
causedby the footbeingsteppedonbyanotherT.rex if a few were “battlingoveracorpse”i
.
Withthisinjury,as a predator,itwouldhave beenimpossible foraT.rex to huntfor food.It
ispossible thata T.rex couldhave changedfrompredationtoscavengingtoobtainfoodbutthisis
unlikely.Sue wouldhave hadthe bestchance forsurvival if she hadbeenanobligate scavenger.
Ecosystem
ChrisCarbone and team(at the Zoological Societyof London) conductedastudycalculating
“the range inwhichT.rex couldroam on a dailybasis,how manydeaddinosaursitwaslikelyto
come across and whatotherforagersmightbe around”xxix
.
His researchconcludedthat“itisextremelyunlikelythatanadultT.rex coulduse scavenging
as a long-termsustainable foragingstrategy”xxix
as“fossil recordsshow thatthe ecosystematthe
time wouldhave beenoverwhelminglypopulatedbysmallerdinosaurs”xxix
.
Thisresearchsupportsthe T.rex beinga predatorassumingthatthe proportionsof
dinosaursof differentsizeswill notchange asnew dinosaursare discovered.“There isanew species
describedevery sevenweeksonaverage”i
saysJackHorner.In time,the proportionof larger
dinosaursthatwere inthe populationmayincrease asmore fossilsare uncovered.

18. 18
Conclusion
There are twotypesof science.One iswhere youlookatthe evidenceanddraw conclusions
fromit. The otheris where youhave a pre-decidedconclusionandfindevidence tosupportit.I
believethe firstisbetterasitavoidsbias.Howevermanyscientistsuse the secondwithregardto
the predator/scavengerargument.
As withmanyaspectsof science,there is nodefiniteanswer.We canonlygive the best
estimate withthe evidencewe have atthe time.
As a resultof my research Ihave concluded the following:
 The teethwere the wrongshape and size tohave beenusedtokill.
 Teethmarksleftonboneswere leftbythatof a scavenger.
 Brain proportionsfollow the patternof modernscavengers.
 The arms were of little use bothincombatand if the T.rex were tofall over.
 Reachinghighspeedswouldhave beenimpossible.
I believe itisnearimpossibleforthe T.rex tohave usedpredationasthe mainsource of its
food.The vast majorityof evidence supportsthisviewwithafew exceptionsthatcouldbe applicable
to eitherpredatororscavenger.Manyargumentssupportingthe T.rex beingapredatorhave now
beendisproveddue toimprovementinanalytical techniquesorsimplybytakinganotherlookatthe
fossils.
I am not suggestinghowever,thatitisimpossible thatif aT.rex were toencounterananimal
on itslastlegsthat it wouldn’thave beenabletokill it.
I wouldlove tobelieve thatthe T.rex hadbeenthe diabolical murdererthatitismade out to
be in the mediaandscientificstudiesbutthe evidence doesnotsupportthishypothesis.

19. 19
Appendix 1 – Statistical Analysis
From the statistical analysis,Ihave removedthe platypusbecause itsspeedwasmeasured
as it movesthroughwater;the lemur,rat,penguin,skunkandmaraas theirsmall size limitsthe
speedatwhichtheytravel andthe pigas it hasbeenbreedtobe sooverweightthatthisaffectshow
fastit can move.
x
(ratio)
y
(speed)
X2
Y2
xy
0.88 42.50 0.7744 1806.2500 37.4000
0.65 15.53 0.4225 241.1809 10.0945
0.55 25.00 0.3025 625.0000 13.7500
0.77 22.00 0.5925 484.0000 16.9400
1.00 35.00 1.0000 1225.0000 35.0000
1.38 25.50 1.9044 650.2500 35.1900
0.60 25.00 0.3600 625.0000 15.0000
0.87 31.00 0.7569 961.0000 26.9700
0.88 35.00 0.7744 1225.0000 30.8000
1.03 30.00 1.0609 900.0000 30.9000
0.88 35.00 0.7744 1225.0000 30.8000
0.87 25.00 0.7569 625.0000 21.7500
1.04 30.00 1.0816 900.0000 31.2000
1.04 43.00 1.0816 1849.0000 44.7200
1.79 40.00 3.2041 1600.0000 71.6000
Σx
14.23
Σy
459.53
Σx2
14.8475
Σy2
14941.6800
Σxy
452.1145
Total Sample Size (n) =15
Sxx= Σx2
– ( (Σx)2
/n)
= 14.8475 – (14.232
/15)
= 1.34797
Syy= Σy2
– ( (Σy)2
/n)

20. 20
= 14941.68 – (459.532
/15)
= 863.82527
Sxy= Σxy – ( (ΣxΣy)/n)
= 452.1145 – ((14.23x459.53)/15)
= 16.17371
PMCC (r)
r = Sxy/ [√(Sxx x Syy)]
= 16.17371/ [√(1.3497 x 863.82527)]
= 0.4743...
= 0.47
0<r<1 therefore positivecorrelation
RegressionLine
b = Sxy/Sxx
= 16.17371 / 1.34797
= 11.99857
a = (Σy/n) – [bx (Σx/n)]
= (459.53/15) – [11.99857 x (14.23/15)]
= 19.25269
y = a + bx
y = 19.25269 + 11.99857x
whenx = 0.92
y = 30.29
thisisinterpolationas0.92 is between0.55and 1.79
Estimated Speed:30.29mph

21. 21
Reference and Bibliography
i The Complete T.Rex by Jack Horne and Don Lesson - Souvenir Press (1993)
ii Dinosaur by Dr David Norman and Dr Angela Milner – HarperCollins(1992)
iii Dinosaurs by StephanieTurnbull – Usborne (2003)
iv Dangerous Dinosaurs by Adam Hibbert – Ticktock Media Ldt. (1999)
v
http://www.ucmp.berkeley.edu/diapsids/saurischia/tyrannosauridae.html
vi London’s Natural History Museum
vii Dinosaurs by Dougal Dixon – Hamlyn (1988)
viii
http://www.dinosaur-world.com/tyrannosaurs/0_tyrannosaurs.htm
ix BBC Documentary – Planet Dinosaur (2011)
x Dinosaurs by Rachel Firth – Usborne (2001)
xi Dinosaurs and Prehistoric Lifeby Hazel Richardson –DorlingKindersley Publishers(2003)
xii New Insights into the Brain,Braincase,and Ear Region of Tyrannosaurus (Dinosauria,Theropoda),with
Implicationsfor Sensory Organisation and Behaviour by Lawrence M. Witmer and Ryan C. Ridgely – paper
published in The Anatomical Record (2009)
xiii http://dinosaurs.about.com/od/dinosaur controversies/a/trexhunter.htm
xiv Discovery Channel Documentary – Valley of the T.rex (2001)
xv Dinosaur Atlas by Tony Gibbons and Robert Shedelon – Parragon (2002)
xvi Principles of Locomotion: Functional Morphology and Artistic Reconstructions by David Polly –Department
of Geological Sciences atIndiana University (2011)
xviihttp://www.bio.davidson.edu/people/midorcas/animalphysiology/websites/2011/Ptaschinski/Builtforspeed
.htm
xviii http://en.wikipedia.org/wiki/Tyrannosaurus
xix Paper by Lawrence M. Witmer and Ryan C. Ridgely – The Anatomical Record vol. 291 no.11 (2008)
xx The age of the dinosaursby David Lambert – Kingfisher Books (1987)
xxi Limb Design, Function and Running Performance in Ostrich –Mimics and Tyrannosaurus by Gregory S. Paul –
Paper published in GAIA (1998)
xxii Principles of Animal Locomotion by R. McNeill Alexander – Princeton University Press (2006)
xxiii http://news.softpedia.com/news/T-rex-was-slow-and-clumsy-56469.shtml
xxiv http://www.rvc.ac.uk/SML/Projects/TRex/Summary.cfm
xxv Tyrannosaurus Was Nota FastRunner by John R. Hutchinson and Marlano Garcla –
http://www.rvc.ac.uk/aboutus/staff/jhutchinson/files/JRH5.pdf
xxvi http://www.nature.com/news/2002/020228/full/news020225-5.html
xxvii The Kingfisher Illustrated Dinosaur Encyclopediaby David Burnie – Kingfisher (2001)
xxviii http://news.nationalgeographic.com/news/2010/06/100629-science-dinosaurs-t-rex-nerves-elephants/
xxix http://news.discovery.com/animals/dinosaurs/tyrnnosaurus-rex-hunter-scavenger-110126.htm
Other Sources
 A Dinosaur Lifeby Dr Brian Knapp
 FirstEncyclopaedia of Dinosaursand Prehistoric Lifeby Sam Taplin – Usborne (2004)
 Teratophoneus Curriei articleby BLM
 http://news.nationalgeographic.com/news/2009/08/090811-t-rex-dinosaurs.bully.html
 http://news.bbc.co.uk/l/hi/sci/tech/3112527.stm
 The American Museum of Natural History’s Book of Dinosaurs:and Other Ancient Creatures by Joseph
Wallace
 Dinosaurs:The Textbook by Spencer G. Lucas
 The Dinosaur Heresies by Robert Bakker
 T. Kuhn Meets T.rex: Critical Conversationsand New Directions in ScienceCentres and Science
Museums – Paper in Studies in Science Education vol. 37 (2002)
 Encyclopedia of Dinosaurs Edited by Philip J.Currieand Kevin Padion

22. 22
 The Great Dinosaur Controversy by Keith M. Parsons
 The evolution and Extinction of the Dinosaurs by David E. Fastovsky and David B. Weishampel
 MuscleMoment Arms of Pelvic Limb Muscles of the Ostrich by N. C. Smith, R. C. Payne, K. Jesper and
A. M. Wilson –Paper published in Journal of Anatomy (2007)
 http://www.montana.edu/wwwes/facstaff/horner.htm
 http://videos.howstuffworks.com/discovery/7172-t-rex-brain-clues-video.htm
 http://australianmuseum.net.au/Uploads/Images/8200/T.%252520rex%252520brain%252520cast%2
52520F.112624_.jpg&w=526&h=395&ei=l0xcUJ6TNKO70QXx0oCIBA&zoom=1&iact=rc&dur=70&sig=1
09815355484716038217&page=1&tbnh=145&tbnw=258&start=0&ndsp=14&ved=1t:429,r:0,s:0,i:71&
tx=202&ty=84
 http://www.google.co.uk/imgres?q=T.rex+brain&num=10&hl=en&safe=active&biw=1024&bih=673&t
bm=isch&tbnid=PCtPzW6IJlQ6OM:&imgrefurl=http://australianmuseum.net.au/image/Tyrannosauru
s-rex-brain/&docid=60jklhtxsK2lAM&imgurl
 http://www.ucmp.berkeley.edu/people/padian/home.php
 http://en.wikipedia.org/wiki/Polar_bear
 http://en.wikipedia.org/wiki/Sue_(dinosaur)
Sources of Animal Speeds:
 http://wiki.answers.com/Q/What_is_the_speed_of_a_rhino
 http://wiki.answers.com/Q/What_is_the_speed_of_a_penguin
 http://www.saczoo.org/document.doc?id=270
 http://en.wikipedia.org/wiki/Talk%3AAntelope
 http://a-z-animals.com/animals/platypus/
 http://a-z-animals.com/animals/lemur/
 http://a-z-animals.com/animals/skunk/
 http://a-z-animals.com/animals/rat/
 http://a-z-animals.com/animals/gibbon/
 http://a-z-animals.com/animals/sheep/
 http://a-z-animals.com/animals/chimpanzee/
 http://a-z-animals.com/animals/wallaby/
 http://www.fossilguy.com/articles/montana_tric/tric_topic.htm