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{{Taxobox
== TORE SHIT UP ==
| name = ''Tyrannosaurus''
'''
| fossil_range = {{fossil range|68.5|65.5}}]
| image = Palais de la Decouverte Tyrannosaurus rex p1050042.jpg
| image_width = 200px
| image_caption = ''T. rex'' skull, Palais de la Découverte, Paris.
| regnum = ]ia
| phylum = ]
| classis = ]
| superordo = ]ia
| ordo = ]
| subordo = ]
| familia = ]
| subfamilia = ]
| genus = '''''Tyrannosaurus'''''
| genus_authority = ], 1905
| subdivision_ranks = ]
| subdivision =
* ''T. rex'' <small>(])</small><br/><small>Osborn, 1905</small>
| synonyms =
* ''Manospondylus'' <br/><small>], 1892</small>
* ''Dynamosaurus'' <br/><small>], 1905</small>
* ?'']'' <br/><small>], Williams & ], 1988</small>
* ''Stygivenator'' <br/><small>], 1995</small>
* ''Dinotyrannus'' <br/><small>], 1995</small>
}}

'''''Tyrannosaurus''''' ({{pronEng|tɨˌrænəˈsɔrəs/ or /taɪˌrænoʊˈsɔrəs}}, meaning 'tyrant lizard') is a ] of ] ]. The famous ] '''''Tyrannosaurus rex''''' ('rex' meaning 'king' in Latin), commonly abbreviated to '''''T. rex''''', is a fixture in ] around the world. It lived throughout what is now western ], with a much wider range than other tyrannosaurids. ]s of ''T. rex'' are found in a variety of ] dating to the last three million years of the ] ], approximately 68 to 65&nbsp;]; it was among the last dinosaurs to exist prior to the ].

Like other tyrannosaurids, ''Tyrannosaurus'' was a ]al ] with a massive ] balanced by a long, heavy tail. Relative to the large and powerful hindlimbs, ''Tyrannosaurus'' forelimbs were small, though unusually powerful for their size, and bore two primary digits, along with a possible third ] digit. Although other theropods rivaled or exceeded ''T. rex'' in ], it was the largest known tyrannosaurid and one of the largest known land predators, measuring up to 13&nbsp;] (43&nbsp;]) in length,<ref name="brochu2003">Brochu, C.R. 2003. Osteology of ''Tyrannosaurus rex'': insights from a nearly complete skeleton and high-resolution computed tomographic analysis of the skull. ''Memoirs of the Society of Vertebrate Paleontology''. 7: 1-138.</ref> up to 4&nbsp;meters (13&nbsp;ft) tall at the hips,<ref name=SueFMNH/> and up to 6.8&nbsp;] (7.5&nbsp;]) in weight.<ref name=ericksonetal2004>{{cite_journal |last=Erickson, Gregory M. |coauthors=Makovicky, Peter J.; ]; Norell, Mark A.; Yerby, Scott A.; & Brochu, Christopher A. |year=2004 |title=Gigantism and comparative life-history parameters of tyrannosaurid dinosaurs |journal=Nature |volume=430 |issue=7001 |pages=772–775 |doi=10.1038/nature02699}}</ref> By far the largest carnivore in its environment, ''T. rex'' may have been an ], preying upon ]s and ]ns, although some experts have suggested it was primarily a ].

More than 30&nbsp;specimens of ''T. rex'' have been identified, some of which are nearly complete skeletons. ] and ]s have been reported in at least one of these specimens. The abundance of fossil material has allowed significant research into many aspects of its ], including life history and ]. The feeding habits, ] and potential speed of ''T. rex'' are a few subjects of debate. Its ] is also controversial, with some scientists considering '']'' from ] to represent a second species of ''Tyrannosaurus'' and others maintaining ''Tarbosaurus'' as a separate genus. Several other genera of North American tyrannosaurids have also been ] with ''Tyrannosaurus''.

==Description==
]
''Tyrannosaurus rex'' was one of the largest land carnivores of all time; the largest complete specimen, ] PR2081 ("]"), measured 12.8&nbsp;]s (42&nbsp;]) long, and was 4.0&nbsp;meters (13&nbsp;ft) tall at the hips.<ref name=SueFMNH>{{cite web |url=http://www.fieldmuseum.org/sue/about_vital.asp |title=Sue's vital statistics |author= |work=Sue at the Field Museum |publisher=] |accessdate=2007-09-15}}</ref> Mass estimates have varied widely over the years, from more than 7.2&nbsp;metric tons (8&nbsp;short tons),<ref name=henderson1999>{{cite_journal |last=Henderson, Donald M. |year=1999 |title=Estimating the masses and centers of mass of extinct animals by 3-D mathematical slicing |journal=Paleobiology |volume=25 |issue=1 |pages=88–106 |url=http://paleobiol.geoscienceworld.org/cgi/content/abstract/25/1/88}}</ref> to less than 4.5&nbsp;metric tons (5&nbsp;tons),<ref name=andersonetal1985>{{cite_journal |last=Anderson |first=John F. |coauthors=Hall-Martin, Anthony J.; & ] |year=1985 |title=Long bone circumference and weight in mammals, birds and dinosaurs |journal=Journal of Zoology |volume=207 |issue=1 |pages=53–61}}</ref><ref name=bakker1986>{{cite_book |last=Bakker |first=Robert T. |authorlink=Robert T. Bakker |year=1986 |title=The Dinosaur Heresies |location=New York |publisher=Kensington Publishing |pages=481pp |isbn=978-0688042875}}</ref> with most modern estimates ranging between 5.4 and 6.8&nbsp;metric tons (between 6 and 7.5&nbsp;tons).<ref name=farlowetal1995>{{cite_journal |last=Farlow |first=James O. |authorlink=James Farlow |coauthors=Smith, Matthew B.; & Robinson, John M. |year=1995 |title=Body mass, bone "strength indicator", and cursorial potential of ''Tyrannosaurus rex'' |journal=Journal of Vertebrate Paleontology |volume=15 |issue=4 |pages=713–725 |url=http://www.vertpaleo.org/publications/jvp/15-713-725.cfm}}</ref><ref name=seebacher2001>{{cite_journal |last=Seebacher |first=Frank. |year=2001 |title=A new method to calculate allometric length-mass relationships of dinosaurs |journal=Journal of Vertebrate Paleontology |volume=21 |issue=1 |pages=51–60 |doi=10.1671/0272-4634(2001)021%5B0051:ANMTCA%5D2.0.CO;2}}</ref><ref name=christiansenfarina2004>{{cite_journal |last=Christiansen |first=Per |coauthors=& Fariña, Richard A. |year=2004 |title=Mass prediction in theropod dinosaurs |journal=Historical Biology |volume=16 |issue=2-4 |pages=85–92 |doi=10.1080/08912960412331284313}}</ref><ref name=ericksonetal2004>{{cite_journal |last=Erickson, Gregory M. |coauthors=Makovicky, Peter J.; ]; Norell, Mark A.; Yerby, Scott A.; & Brochu, Christopher A. |year=2004 |title=Gigantism and comparative life-history parameters of tyrannosaurid dinosaurs |journal=Nature |volume=430 |issue=7001 |pages=772–775 |doi=10.1038/nature02699}}</ref> Although ''Tyrannosaurus rex'' was larger than the well known ] theropod '']'', it was slightly smaller than Cretaceous carnivores '']'' and '']''.<ref name=dalsassoetal2005>{{cite_journal |last=dal Sasso |first=Cristiano |coauthors=Maganuco, Simone; Buffetaut, Eric; & Mendez, Marcos A. |year=2005 |title=New information on the skull of the enigmatic theropod ''Spinosaurus'', with remarks on its sizes and affinities |journal=Journal of Vertebrate Paleontology |volume=25 |issue=4 |pages=888-896 | url=http://www.bioone.org/perlserv/?request=get-abstract&doi=10.1671%2F0272-4634%282005%29025%5B0888%3ANIOTSO%5D2.0.CO%3B2
|doi=10.1671/0272-4634(2005)025%5B0888:NIOTSO%5D2.0.CO;2
|doilabel=10.1671/0272-4634(2005)025%5B0888:NIOTSO%5D2.0.CO;2}}</ref><ref name=calvocoria1998>{{cite journal |last=Calvo |first=Jorge O. |authorlink=Jorge Calvo |coauthors=& ] |date=1998 |title=New specimen of ''Giganotosaurus carolinii'' (Coria & Salgado, 1995), supports it as the as the largest theropod ever found |journal=Gaia |volume=15 | pages=117–122 |url=http://www.mnhn.ul.pt/geologia/gaia/7.pdf}} </ref>
]
The neck of ''T. rex'' formed a natural S-shaped curve like that of other theropods, but was short and muscular to support the massive head. The forelimbs were long thought to bear only two digits, but there is an unpublished report of a third, vestigial digit in one specimen.<ref name=quinlanetal2007>{{cite_journal |last=Quinlan |first=Elizibeth D. |coauthors=Derstler, Kraig; & Miller, Mercedes M. |year=2007 |title=Anatomy and function of digit III of the ''Tyrannosaurus rex'' manus |journal=Geological Society of America Annual Meeting - Abstracts with Programs |pages=77 |url=http://gsa.confex.com/gsa/2007AM/finalprogram/abstract_132345.htm}} </ref> In contrast the hind limbs were among the longest in proportion to body size of any theropod. The tail was heavy and long, sometimes containing over forty ]e, in order to balance the massive head and torso. To compensate for the immense bulk of the animal, many bones throughout the skeleton were hollow, reducing its weight without significant loss of strength.<ref name="brochu2003"/>

The largest known ''T. rex'' skulls measure up to 1.5&nbsp;meters (5&nbsp;ft) in length. Large ''fenestrae'' (openings) in the skull reduced weight and provided areas for muscle attachment, as in all carnivorous theropods. But in other respects ''Tyrannosaurus''’ skull was significantly different from those of large non-] theropods. It was extremely wide at the rear but had a narrow snout, allowing unusually good ].<ref name="Stevens2006Binocular" /> The skull bones were massive and the ] and some other bones were fused, preventing movement between them; but many were pneumatized (contained a "honeycomb" of tiny air spaces) which may have made the bones more flexible as well as lighter. These and other skull-strengthening features are part of the ] trend towards an increasingly powerful bite, which easily surpassed that of all non-tyrannosaurids.<ref name="SnivelyHendersonPhillips2006FusedVaultedNasals">{{cite journal
| authors=Snively, E., Henderson, D.M., and Phillips, D.S.
| date= 2006
| title== Fused and vaulted nasals of tyrannosaurid dinosaurs: Implications for cranial strength and feeding mechanics
| journal=Acta Palaeontologica Polonica
| volume=51
| issue=3
| pages=435–454
}}</ref> <ref name=GEetal96>{{cite journal |last=Erickson |first=G.M. |coauthors=Van Kirk, S.D.; Su, J.; Levenston, M.E.; Caler, W.E.; and Carter, D.R. |year=1996 |title=Bite-force estimation for ''Tyrannosaurus rex'' from tooth-marked bones. |journal=Nature |volume=382 |pages=706–708 }}</ref><ref name=MM03>{{cite journal |last=Meers |first=M.B. |year=August 2003 |url= http://www.ingentaconnect.com/content/tandf/ghbi/2003/00000016/00000001/art00001 |title=Maximum bite force and prey size of ''Tyrannosaurus rex'' and their relationships to the inference of feeding behavior |journal=Historical Biology: A Journal of Paleobiology |volume=16 |issue=1 |pages=1–12 |doi=10.1080/0891296021000050755}}</ref> The tip of the upper jaw was U-shaped (most non-tyrannosauroid carnivores had V-shaped upper jaws), which increased the amount of tissue and bone a tyrannosaur could rip out with one bite, although it also increased the stresses on the front teeth.<ref name="holtz1994" /><ref name="paul1988" />

The teeth of ''T. rex'' displayed marked ]y (differences in shape).<ref name="Smith2005HeterodontyTRex">{{ cite journal | author=Smith, J.B. | title=Heterodonty in ''Tyrannosaurus rex'': implications for the taxonomic and systematic utility of theropod dentitions
| journal=Journal of Vertebrate Paleontology | volume=25 | issue=4 | pages=865–887 | date=December 2005 |url=http://www.bioone.org/perlserv/?request=get-document&doi=10.1671%2F0272-4634(2005)025%5B0865%3AHITRIF%5D2.0.CO%3B2
| doi=10.1671/0272-4634(2005)0252.0.CO;2}} Copy at </ref><ref name="brochu2003">{{cite journal |last=Brochu |first=C.R. |year=2003 |title=Osteology of ''Tyrannosaurus rex'': insights from a nearly complete skeleton and high-resolution computed tomographic analysis of the skull |journal=Society of Vertebrate Paleontology Memoirs |volume=7 |pages=1–138}}</ref>
The ]ry teeth at the front of the upper jaw were closely-packed, D-shaped in cross-section, had reinforcing ridges on the rear surface, were ] (their tips were chisel-like blades) and curved backwards. The D-shaped cross-section, reinforcing ridges and backwards curve reduced the risk that the teeth would snap when ''Tyrannosaurus'' bit and pulled. The remaining teeth were robust, like "lethal bananas" rather than daggers, more widely spaced and also had reinforcing ridges.<ref "New Scientist1998DinosaurDetectives">{{ cite web | title=The dinosaur detectives | date=18 April 1998 | publisher=New Scientist | authors=Douglas, K. and Young, S. | url=http://www.newscientist.com/channel/life/dinosaurs/mg15821305.300}} Kevin Padian coined the phrase "lethal bananas".</ref> Those in the upper jaw were larger than those in all but the rear of the lower jaw. The largest found so far is estimated to have been 30&nbsp;centimeters (12&nbsp;in) long including the root when the animal was alive, making it the largest tooth of any carnivorous dinosaur.<ref name="gll">{{cite web |title=All About Sue|publisher=The Field Museum|url=http://www.fieldmuseum.org/sue/about_vital.asp|accessdate=2007-11-16 }}</ref>

==Classification==
].]]
''Tyrannosaurus'' is the ] genus of the superfamily ], the ] ], and the subfamily Tyrannosaurinae; in other words it is the standard by which paleontologists decide whether to include other species in the same group. Other members of the tyrannosaurine subfamily include the North American '']'' and the ]n ''Tarbosaurus'',<ref name="currieetal2003">Currie, P.J., Hurum, J.H., and Sabath, K. 2003. Skull structure and evolution in tyrannosaurid dinosaurs. ''Acta Palaeontologica Polonica'' 48(2): 227–234. (download )</ref><ref name="holtz2004">Holtz, T.R. 2004. Tyrannosauroidea. In: Weishampel, D.B., Dodson, P., & Osmolska, H. (Eds.). ''The Dinosauria'' (2nd Edition). Berkeley: University of California Press. Pp. 111–136.</ref> both of which have occasionally been synonymized with ''Tyrannosaurus''.<ref name="paul1988">Paul, G.S. 1988. ''Predatory Dinosaurs of the World''. New York: Simon & Schuster. 464pp.</ref> Tyrannosaurids were once commonly thought to be descendants of earlier large theropods such as ] and ], although more recently they were reclassified with the generally smaller ].<ref name="holtz1994">Holtz, T.R. 1994. The phylogenetic position of the Tyrannosauridae: implications for theropod systematics. ''Journal of Palaeontology'' 68(5): 1100–1117.</ref>

In 1955, ] ] ] named a new species, ''Tyrannosaurus bataar'', from ].<ref name="maleev1955">Maleev, E.A. 1955. . ''Doklady Akademii Nauk S.S.S.R.'' 104(4): 634–637. </ref> By 1965, this species had been renamed ''Tarbosaurus bataar''.<ref name="rozhdestvensky1965">Rozhdestvensky, A.K. 1965. Growth changes in Asian dinosaurs and some problems of their taxonomy. 3: 95–109.</ref> Despite the renaming, many ] analyses have found ''Tarbosaurus bataar'' to be the ] of ''Tyrannosaurus rex'',<ref name="holtz2004"/> and it has often been considered an Asian species of ''Tyrannosaurus''.<ref name="holtz1994"/><ref name="carpenter1992">Carpenter, K. 1992. Tyrannosaurids (Dinosauria) of Asia and North America. In: Mateer, N. & Chen P. (Eds.). ''Aspects of Nonmarine Cretaceous Geology''. Beijing: China Ocean Press Pp. 250–268. (download )</ref><ref name="carretal2005">Carr, T.D., Williamson, T.E., & Schwimmer, D.R. 2005. A new genus and species of tyrannosauroid from the Late Cretaceous (Middle Campanian) Demopolis Formation of Alabama. ''Journal of Vertebrate Paleontology'' 25(1): 119–143.</ref> A recent redescription of the skull of ''Tarbosaurus bataar'' has shown that it was much narrower than that of ''Tyrannosaurus rex'' and that during a bite, the distribution of stress in the skull would have been very different, closer to that of '']'', another Asian tyrannosaur.<ref name="hurumsabath2003">Hurum, J.H. & Sabath, K. 2003. Giant theropod dinosaurs from Asia and North America: Skulls of ''Tarbosaurus bataar'' and ''Tyrannosaurus rex'' compared. ''Acta Palaeontologica Polonica'' 48(2): 161–190. (download )</ref> A related ] analysis found that ''Alioramus'', not ''Tyrannosaurus'', was the sister taxon of ''Tarbosaurus'', which, if true, would suggest that ''Tarbosaurus'' and ''Tyrannosaurus'' should remain separate.<ref name="currieetal2003"/>

Other tyrannosaurid fossils found in the same formations as ''T. rex'' were originally classified as separate taxa, including ''Aublysodon'' and ''Albertosaurus megagracilis'',<ref name="paul1988"/> the latter being named ''Dinotyrannus megagracilis'' in 1995.<ref name="Olshevsky1995">{{cite journal |last=Olshevsky |first=George |authorlink=George Olshevsky |year=1995 |title=The origin and evolution of the tyrannosaurids |journal=Kyoryugaku Saizensen |volume=9–10 |pages=92–119 (9) 75–99 (10)}}</ref> However, these fossils are now universally considered to belong to juvenile ''T. rex''.<ref name="carrwilliamson2004">Carr, T.D. & Williamson, T.E. 2004. Diversity of late Maastrichtian Tyrannosauridae (Dinosauria: Theropoda) from western North America. ''Zoological Journal of the Linnean Society'' 142: 479–523.</ref> A small but nearly complete skull from Montana, 60&nbsp;cm (2&nbsp;ft) long, may be an exception. This skull was originally classified as a species of '']'' (''G. lancensis'') by ] in 1946,<ref name="gilmore1946">Gilmore, C.W. 1946. A new carnivorous dinosaur from the Lance Formation of Montana. ''Smithsonian Miscellaneous Collections'' 106: 1–19.</ref> but was later referred to a new genus, '']''.<ref name="bakkeretal1988">Bakker, R.T., Williams, M., & Currie, P.J. 1988. ''Nanotyrannus'', a new genus of pygmy tyrannosaur, from the latest Cretaceous of Montana. ''Hunteria'' 1(5): 1–30.</ref> Opinions remain divided on the validity of ''N. lancensis''. Many paleontologists consider the skull to belong to a juvenile ''T. rex''.<ref name="carr1999">Carr TD. 1999. Craniofacial ontogeny in Tyrannosauridae (Dinosauria, Theropoda). ''Journal of Vertebrate Paleontology'' 19: 497–520.</ref> There are minor differences between the two species, including the higher number of teeth in ''N. lancensis'', which lead some scientists to recommend keeping the two genera separate until further research or discoveries clarify the situation.<ref name="holtz2004"/><ref name="currie2003">Currie, P.J. 2003. Cranial anatomy of tyrannosaurid dinosaurs from the Late Cretaceous of Alberta, Canada. ''Acta Palaeontologica Polonica'' 48(2): 191–226. (download )</ref>

===''Manospondylus''===
] specimen at the ]. This was heavily and inaccurately restored with plaster after '']'', and has since been disassembled.]]
The first fossil specimen which can be attributed to ''Tyrannosaurus rex'' consists of two partial vertebrae (one of which has been lost) found by ] in 1892 and described as ''Manospondylus gigas''. Osborn recognized the similarity between ''M. gigas'' and ''T. rex'' as early as 1917 but, due to the fragmentary nature of the ''Manospondylus'' vertebrae, he could not synonymize them conclusively.<ref name="osborn1917">Osborn, H.F. 1917. Skeletal adaptations of ''Ornitholestes'', ''Struthiomimus'', ''Tyrannosaurus''. ''Bulletin of the American Museum of Natural History'' 35: 733–71.</ref>

In June 2000, the ] located the type locality of ''M. gigas'' in South Dakota and unearthed more tyrannosaur bones there. These were judged to represent further remains of the same individual, and to be identical to those of ''T. rex''. According to the rules of the ] (ICZN), the system that governs the scientific naming of animals, ''Manospondylus gigas'' should therefore have priority over ''Tyrannosaurus rex'', because it was named first.<ref name="mccormick2000">"" by David McCormick. Discovery Channel Canada. ] ]. Accessed ] ].</ref> However, the Fourth Edition of the , which took effect on ] ], states that "the prevailing usage must be maintained" when "the senior synonym or homonym has not been used as a valid name after 1899" and "the junior synonym or homonym has been used for a particular taxon, as its presumed valid name, in at least 25 works, published by at least 10 authors in the immediately preceding 50 years…"<ref name="icznart23">International Code of Zoological Nomenclature, Fourth Edition. . International Commission on Zoological Nomenclature. ] ]. Accessed ] ].</ref> ''Tyrannosaurus rex'' easily qualifies as the valid name under these conditions and would most likely be considered a '']'' ("protected name") under the ICZN if it was ever challenged, which it has not yet been. ''Manospondylus gigas'' would then be deemed a '']'' ("forgotten name").<ref name="taylor2002">"" by Mike Taylor. ] ]. Accessed ] ].</ref>

==Paleobiology==
===Life history===
]
The identification of several specimens as juvenile ''Tyrannosaurus rex'' has allowed scientists to document ] changes in the species, estimate the lifespan, and determine how quickly the animals would have grown. The smallest known individual (] 28471, the "Jordan theropod") is estimated to have weighed only 29.9&nbsp;kg (66&nbsp;lb), while the largest, such as ] PR2081 ("]") most likely weighed over 5400&nbsp;kg (6&nbsp;]). ] analysis of ''T. rex'' bones showed LACM 28471 had aged only 2 years when it died, while "Sue" was 28 years old, an age which may have been close to the maximum for the species.<ref name="ericksonetal2004">Erickson, G.M., Makovicky, P.J., Currie, P.J., Norell, M.A., Yerby, S.A. & Brochu, C.A. 2004. Gigantism and comparative life-history parameters of tyrannosaurid dinosaurs. ''Nature'' 430: 772–775.</ref>

Histology has also allowed the age of other specimens to be determined. Growth curves can be developed when the ages of different specimens are plotted on a graph along with their mass. A ''T. rex'' growth curve is S-shaped, with juveniles remaining under 1800&nbsp;kg (2&nbsp;short tons) until approximately 14 years of age, when body size began to increase dramatically. During this rapid growth phase, a young ''T. rex'' would gain an average of 600&nbsp;kg (1,300&nbsp;lb) a year for the next four years. At 18 years of age, the curve plateaus again, indicating that growth slowed dramatically. For example, only 600&nbsp;kg (1,300&nbsp;lb) separated the 28-year-old "Sue" from a 22-year-old ] specimen (] 81.12.1).<ref name="ericksonetal2004"/> Another recent histological study performed by different workers corroborates these results, finding that rapid growth began to slow at around 16 years of age.<ref name="hornerpadian2004">Horner, J.R. & Padian, K. 2004. Age and growth dynamics of Tyrannosaurus rex. ''Proceedings of the Royal Society of London B'' 271: 1875–1880.</ref> This sudden change growth rate may indicate physical maturity, a hypothesis which is supported by the discovery of medullary tissue in the ] of a 16 to 20-year-old ''T. rex'' from Montana (] 1125, also known as "B-rex"). Medullary tissue is found only in female birds during ovulation, indicating that "B-rex" was of reproductive age.<ref name="schweitzeretal2005">Schweitzer, M.H., Wittmeyer, J.L., & Horner, J.R. 2005. Gender-specific reproductive tissue in ratites and ''Tyrannosaurus rex''. ''Science'' 308: 1456–1460.</ref> Further study indicates an age of 18 for this specimen.<ref name=LW08>{{cite journal |last=Lee |first=Andrew H. |coauthors=and Werning, Sarah |year=2008 |title=Sexual maturity in growing dinosaurs does not fit reptilian growth models |journal=Proceedings of the National Academy of Sciences |volume=105 |issue=2 |pages=582-587 |doi=10.1073/pnas.0708903105}}</ref> Other tyrannosaurids exhibit extremely similar growth curves, although with lower growth rates corresponding to their lower adult sizes.<ref name="ericksonetal2006">Erickson, G.M., Currie, P.J., Inouye, B.D., & Winn, A.A. 2006. Tyrannosaur life tables: an example of nonavian dinosaur population biology. ''Science'' 313: 213–217.</ref>

Over half of the known ''T. rex'' specimens appear to have died within six years of reaching sexual maturity, a pattern which is also seen in other tyrannosaurs and in some large, long-lived birds and mammals today. These species are characterized by high infant mortality rates, followed by relatively low mortality among juveniles. Mortality increases again following sexual maturity, partly due to the stresses of reproduction. One study suggests that the rarity of juvenile ''T. rex'' fossils is due in part to low juvenile mortality rates; the animals were not dying in large numbers at these ages, and so were not often fossilized. However, this rarity may also be due to the incompleteness of the ] or to the bias of fossil collectors towards larger, more spectacular specimens.<ref name="ericksonetal2006"/>

===Sexual dimorphism===
]
As the number of specimens increased, scientists began to analyze the variation between individuals and discovered what appeared to be two distinct body types, or ''morphs'', similarly to some other theropod species. As one of these morphs was more solidly built, it was termed the 'robust' morph while the other was termed '].' Several ] differences associated with the two morphs were used to analyze ] in ''Tyrannosaurus rex'', with the 'robust' morph usually suggested to be female. For example, the ] of several 'robust' specimens seemed to be wider, perhaps to allow the passage of ]s.<ref name="carpenter1990">Carpenter, K. 1990. Variation in ''Tyrannosaurus rex''. In: Carpenter, K. & Currie, P.J. (Eds.). ''Dinosaur Systematics: Approaches and Perspectives''. New York: Cambridge University Press. Pp. 141–145. (download )</ref> It was also thought that the 'robust' morphology correlated with a reduced ] on the first tail vertebra, also ostensibly to allow eggs to pass out of the ], as had been erroneously reported for ]s.<ref name="larson1994">Larson, P.L. 1994. ''Tyrannosaurus'' sex. In: Rosenberg, G.D. & Wolberg, D.L. ''Dino Fest''. ''The Paleontological Society Special Publications''. 7: 139–155.</ref>

In recent years, evidence for sexual dimorphism has been weakened. A 2005 study reported that previous claims of sexual dimorphism in crocodile chevron anatomy were in error, casting doubt on the existence of similar dimorphism between ''T. rex'' genders.<ref name="ericksonetal2005">Erickson, G.M., Lappin, A.K., & Larson, P.L. 2005. Androgynous rex. The utility of chevrons for determining the sex of crocodilians and non-avian dinosaurs. ''Zoology'' 108: 277–286.</ref> A full-sized chevron was discovered on the first tail vertebra of "Sue," an extremely robust individual, indicating that this feature could not be used to differentiate the two morphs anyway. As ''T. rex'' specimens have been found from ] to ], differences between individuals may be indicative of geographic variation rather than sexual dimorphism. The differences could also be age-related, with 'robust' individuals being older animals.<ref name="brochu2003"/>

Only a single ''T. rex'' specimen has been conclusively shown to belong to a specific gender. Examination of "B-rex" demonstrated the preservation of soft tissue within several bones. Some of this tissue has been identified as medullary tissue, a specialized tissue grown only in modern birds as a source of calcium for the production of eggshell during ovulation. As only female birds lay eggs, medullary tissue is only found naturally in females, although males are capable of producing it when injected with female reproductive ]s like ]. This strongly suggests that "B-rex" was female, and that she died during ovulation.<ref name="schweitzeretal2005"/> Recent research has shown that medullary tissue is never found in crocodiles, which are thought to be the closest living relatives of dinosaurs, aside from birds. The shared presence of medullary tissue in birds and theropod dinosaurs is further evidence of the close ]ary relationship between the two.<ref name="schweitzeretal2007">Schweitzer, M.H., Elsey, R.M., Dacked, C.G., Horner. J.R., & Lamm, E.-T. 2007. Do egg-laying crocodilian (''Alligator mississippiensis'') archosaurs form medullary bone? ''Bone'' 40 (4): 1152–1158. {{doi|10.1016/j.bone.2006.10.029}}</ref>

===Posture===
]), showing 'tripod' pose.]]
], showing modern view of posture.]]
Like many bipedal dinosaurs, ''Tyrannosaurus rex'' was historically depicted as a 'living tripod', with the body at 45 degrees or less from the vertical and the tail dragging along the ground, similar to a ]. This concept dates from ]'s 1865 reconstruction of '']'', the first to depict a dinosaur in a bipedal posture.<ref name="leidy1865">Leidy, J. 1865. Memoir on the extinct reptiles of the Cretaceous formations of the United States. ''Smithsonian Contributions to Knowledge''. 14: 1–135.</ref> ], former president of the ] (AMNH) in ], who believed the creature stood upright, further reinforced the notion after unveiling the first complete ''T. rex'' skeleton in 1915. It stood in this upright pose for nearly a century, until it was dismantled in 1992.<ref name="amnhsite">"" American Museum of Natural History. (] ]).</ref> By 1970, scientists realized this pose was incorrect and could not have been maintained by a living animal, as it would have resulted in the ] or weakening of several ]s, including the hips and the articulation between the head and the ].<ref name="newman1970">Newman, B.H. 1970. Stance and gait in the flesh-eating ''Tyrannosaurus''. ''Biological Journal of the Linnean Society''. 2: 119–123.</ref> Despite its inaccuracies, the AMNH mount inspired similar depictions in many films and paintings (such as ]'s famous mural '''' in ]'s ]) until the 1990s, when films such as '']'' introduced a more accurate posture to the general public. Modern representations in museums, art, and film show ''T. rex'' with its body approximately parallel to the ground and tail extended behind the body to balance the head.<ref name="paul1988"/>

===Arms===
], ].]]
When ''Tyrannosaurus rex'' was first discovered, the ] was the only element of the forelimb known.<ref name="osborn1905">Osborn, H.F. 1905. ''Tyrannosaurus'' and other Cretaceous carnivorous dinosaurs. ''Bulletin of the American Museum of Natural History'' 21: 259–265. (download )</ref> For the initial mounted skeleton as seen by the public in 1915, Osborn substituted longer, three-fingered forelimbs like those of '']''.<ref name="osborn1917"/> However, a year earlier, ] described the short, two-fingered forelimbs of the closely-related '']''.<ref name="lambe1914">Lambe, L.M. 1914. On a new genus and species of carnivorous dinosaur from the Belly River Formation of Alberta, with a description of the skull of ''Stephanosaurus marginatus'' from the same horizon. ''Ottawa Naturalist'' 27: 129–135.</ref> This strongly suggested that ''T. rex'' had similar forelimbs, but this ] was not confirmed until the first complete ''T. rex'' forelimbs were identified in 1989, belonging to MOR 555 (the "Wankel rex").<ref name="hornerlessem1993">Horner, J.R. & Lessem, D. 1993. ''The Complete T. rex: How Stunning New Discoveries Are Changing Our Understanding of the World's Most Famous Dinosaur''. New York: Simon & Schuster. 235pp.</ref> The remains of "Sue" also include complete forelimbs.<ref name="brochu2003"/> ''T. rex'' 'arms' are very small relative to overall body size, measuring only 1&nbsp;m (3&nbsp;ft 3&nbsp;in) long. However, they are not ] but instead show large areas for ] attachment, indicating considerable strength. This was recognized as early as 1906 by Osborn, who speculated that the forelimbs may have been used to grasp a mate during ].<ref name="osborn1906">Osborn, H.F. 1906. ''Tyrannosaurus'', Upper Cretaceous carnivorous dinosaur (second communication). ''Bulletin of the American Museum of Natural History''. 22: 281–296. (download )</ref> It has also been suggested that the forelimbs were used to assist the animal in rising from a prone position.<ref name="newman1970"/> Another possibility is that the forelimbs held struggling prey while it was dispatched by the tyrannosaur's enormous jaws. This hypothesis may be supported by ] analysis. ''T. rex'' forelimb bones exhibit extremely thick ], indicating that they were developed to withstand heavy loads. The ] muscle of a full-grown ''Tyrannosaurus rex'' was capable of lifting 199&nbsp;kg (438&nbsp;lb) by itself; this number would only increase with other muscles (like the ]) acting in concert with the biceps. A ''T. rex'' forearm also had a reduced range of motion, with the shoulder and elbow joints allowing only 40 and 45 degrees of motion, respectively. In contrast, the same two joints in '']'' allow up to 88 and 130 degrees of motion, respectively, while a human arm can rotate 360 degrees at the shoulder and move through 165 degrees at the elbow. The heavy build of the arm bones, extreme strength of the muscles, and limited range of motion may indicate a system designed to hold fast despite the stresses of a struggling prey animal.<ref name="carpentersmith2001">Carpenter, K. & Smith, M.B. 2001. Forelimb osteology and biomechanics of ''Tyrannosaurus''. In: Tanke, D.H. & Carpenter, K. (Eds.). ''Mesozoic Vertebrate Life''. Bloomington: Indiana University Press. Pp. 90–116. (download )</ref>

===Soft tissue===
In the March 2005 issue of '']'', Mary Higby Schweitzer of ] and colleagues announced the recovery of soft tissue from the marrow cavity of a fossilized leg bone, from a 68 million-year-old ''Tyrannosaurus''. The bone had been intentionally, though reluctantly, broken for shipping and then not preserved in the normal manner, specifically because Schweitzer was hoping to test it for soft tissue.<ref>{{cite web | title = Dinosaur Shocker|author= Fields, Helen| publisher= '']''| date= May 2006| url= http://www.smithsonianmag.com/science-nature/dinosaur.html| accessdate=2008-03-07}}</ref> Designated as the Museum of the Rockies specimen 1125, or MOR 1125, the dinosaur was previously excavated from the ]. Flexible, bifurcating ]s and fibrous but elastic ] matrix tissue were recognized. In addition, microstructures resembling ]s were found inside the matrix and vessels. The structures bear resemblance to ] blood cells and vessels. Whether an unknown process, distinct from normal fossilization, preserved the material, or the material is original, the researchers do not know, and they are careful not to make any claims about preservation.<ref name=MHSetalb>{{cite journal |last=Schweitzer |first=M.H. coauthors=Wittmeyer, J.L.; Horner, J.R.; and Toporski, J.B. |year=2005 |title=Soft Tissue Vessels and Cellular Preservation in ''Tyrannosaurus rex'' |journal=Science |volume=307 |issue=5717 |pages=1952–1955 |url = http://www.sciencemag.org/cgi/content/full/sci;307/5717/1952#REF1 |doi=10.1126/science.1108397}}</ref> If it is found to be original material, any surviving proteins may be used as a means of indirectly guessing some of the DNA content of the dinosaurs involved, because each protein is typically created by a specific gene. The absence of previous finds may merely be the result of people assuming preserved tissue was impossible, therefore simply not looking. Since the first, two more tyrannosaurs and a hadrosaur have also been found to have such tissue-like structures.<ref>{{cite web | title= Dinosaur Shocker | url=http://www.smithsonianmag.com/issues/2006/may/dinosaur.php | author = Fields, H | publisher = Smithsonian Magazine Online | accessdate = 2006-05-01| accessyear= }}</ref> Research on some of the tissues involved have suggested that birds are closer relatives to tyrannosaurs than other modern animals.<ref>{{cite web| title=Protein links T. rex to chickens|url=http://news.bbc.co.uk/1/hi/sci/tech/6548719.stm|author=Rincon, Paul|accessmonthday=April 12 | accessyear=2007|accessyear= }}</ref>

In studies reported in the journal ''Science'' in April 2007, Asara and colleagues concluded that seven traces of ] proteins detected in purified ''T. rex'' bone most closely match those reported in ]s, followed by frogs and newts. The discovery of proteins from a creature tens of millions of years old, along with similar traces the team found in a mastodon bone at least 160,000 years old, upends the conventional view of fossils and may shift paleontologists' focus from bone hunting to biochemistry. Until these finds, most scientists presumed that fossilization replaced all living tissue with inert minerals. Paleontologist Hans Larsson of McGill University in Montreal, who was not part of the studies, called the finds "a milestone", and suggested that dinosaurs could "enter the field of molecular biology and really slingshot paleontology into the modern world."<ref>. USA Today, April 13, 2007.</ref>

Subsequent studies in April 2008 confirmed the close connection of ''T. rex'' to modern birds. Postdoctoral biology researcher Chris Organ at ] announced, "With more data, they would probably be able to place ''T. rex'' on the evolutionary tree between ]s and chickens and ]es." Co-author John M. Asara added, "We also show that it groups better with birds than modern reptiles, such as alligators and ]."<ref>{{cite web |title=Scientists study evidence modern birds came from dinosaurs |url=http://hosted.ap.org/dynamic/stories/T/T_REX_BIRDS?SITE=ALOPE&SECTION=HOME&TEMPLATE=DEFAULT |author=Randolph E. Schmid |date=April 2008 |publisher=] |accessmonth=April |accessyear=2008}}</ref>

===Skin===
{{main|Feathered dinosaurs}}
].]]
In 2004, the scientific journal '']'' published a report describing an early tyrannosauroid, '']'', from the famous ] of ]. As with many other theropods discovered in the Yixian, the fossil skeleton was preserved with a coat of filamentous structures which are commonly recognized as the precursors of ]s. It has also been proposed that ''Tyrannosaurus'' and other closely-related tyrannosaurids had such protofeathers. However, rare skin impressions from adult tyrannosaurids in Canada and Mongolia show pebbly scales typical of other dinosaurs.<ref></ref> While it is possible that protofeathers existed on parts of the body which have not been preserved, a lack of ] body covering is consistent with modern multi-ton mammals such as ], ], and most species of ]. As an object increases in size, its ability to retain heat increases due to its decreasing ]-to-] ratio. Therefore, as large animals ] in or ] into warm climates, a coat of fur or feathers loses its ] advantage for thermal insulation and can instead become a disadvantage, as the insulation traps excess heat inside the body, possibly overheating the animal. Protofeathers may also have been secondarily lost during the evolution of large tyrannosaurids like ''Tyrannosaurus'', especially in warm Cretaceous climates.<ref name="xuetal2004">Xu X., Norell, M.A., Kuang X., Wang X., Zhao Q., & Jia C. 2004. Basal tyrannosauroids from China and evidence for protofeathers in tyrannosauroids. ''Nature'' 431: 680–684.</ref>

===Thermoregulation===
{{main|Physiology of dinosaurs}}

''Tyrannosaurus'', like most dinosaurs, was long thought to have an ]ic ("cold-blooded") reptilian ]. The idea of dinosaur ectothermy was challenged by scientists like ] and ] in the early years of the "]", beginning in the late 1960s.<ref name="bakker1968">Bakker, R.T. 1968. The superiority of dinosaurs. ''Discovery'' 3: 11–22.</ref><ref name="bakker1972">Bakker, R.T. 1972. Anatomical and ecological evidence of endothermy in dinosaurs. ''Nature'' 238: 81–85.</ref> ''Tyrannosaurus rex'' itself was claimed to have been ]ic ("warm-blooded"), implying a very active lifestyle.<ref name="bakker1986"/> Since then, several paleontologists have sought to determine the ability of ''Tyrannosaurus'' to ] its body ]. Histological evidence of high growth rates in young ''T. rex'', comparable to those of mammals and birds, may support the hypothesis of a high metabolism. Growth curves indicate that, as in mammals and birds, ''T. rex'' growth was limited mostly to immature animals, rather than the ] seen in most other ]s.<ref name="hornerpadian2004"/>

] ] ratios in fossilized bone are sometimes used to determine the temperature at which the bone was deposited, as the ratio between certain isotopes correlates with temperature. In one specimen, the isotope ratios in bones from different parts of the body indicated a temperature difference of no more than 4 to 5] (7 to 9]) between the vertebrae of the torso and the ] of the lower leg. This small temperature range between the body core and the extremities was claimed by paleontologist ] and ] ] to indicate that ''T. rex'' maintained a constant internal body temperature (]y) and that it enjoyed a metabolism somewhere between ectothermic reptiles and endothermic mammals.<ref name="barrettshowers1994">Barrick, R.E. & Showers, W.J. 1994. Thermophysiology of ''Tyrannosaurus rex'': Evidence from oxygen isotopes. ''Science'' 265: 222–224.</ref> Other scientists have pointed out that the ratio of oxygen isotopes in the fossils today does not necessarily represent the same ratio in the distant past, and may have been altered during or after fossilization (]).<ref name="truemanetal2003">Trueman, C., Chenery, C., Eberth, D.A. & Spiro, B. 2003. Diagenetic effects on the oxygen isotope composition of bones of dinosaurs and other vertebrates recovered from terrestrial and marine sediments. ''Journal of the Geological Society, London'' 160: 895–901.</ref> Barrick and Showers have defended their conclusions in subsequent papers, finding similar results in another theropod dinosaur from a different continent and tens of millions of years earlier in time ('']'').<ref name="barrickshowers1999">Barrick, R.E. & Showers, W.J. 1999. Thermophysiology and biology of ''Giganotosaurus'': comparison with ''Tyrannosaurus''. ''Palaeontologia Electronica'' 2 (2): 22pp.</ref> ]n dinosaurs also showed evidence of homeothermy, while ] ]s from the same formation did not.<ref name="barrickstevens1997">Barrick, R.E., Stoskopf, M. & Showers, W.J. 1997. Oxygen isotopes in dinosaur bones. In: Farlow, J.O. & Brett-Surman, M. (Eds.). ''The Complete Dinosaur''. Bloomington: Indiana University Press. Pp. 474–490.</ref> Even if ''Tyrannosaurus rex'' does exhibit evidence of homeothermy, it does not necessarily mean that it was endothermic. Such thermoregulation may also be explained by ], as in some living ]s.<ref name="paladinoetal1997">Paladino, F.V., Spotila, J.R., & Dodson, P. 1997. A blueprint for giants: modeling the physiology of large dinosaurs. In: Farlow, J.O. & Brett-Surman, M. (Eds.). ''The Complete Dinosaur''. Bloomington: Indiana University Press. Pp. 491–504.</ref><ref name="chinsamyhillenius2004">Chinsamy, A. & Hillenius, W.J. 2004. Physiology of nonavian dinosaurs. In: Weishampel, D.B., Dodson, P., & Osmolska, H. (Eds.). ''The Dinosauria'' (2nd Edition). Berkeley: University of California Press. Pp. 643–659.</ref>

===Footprints===
].]]
Two isolated fossilized ]s have been tentatively assigned to ''Tyrannosaurus rex''. The first was discovered in ], ] in 1983 by American geologist Charles Pillmore. Originally thought to belong to a ], examination of the footprint revealed a large 'heel' unknown in ] dinosaur tracks, and traces of what may have been a ], the dewclaw-like fourth digit of the tyrannosaur foot. The footprint was published as the ] ''Tyrannosauripus pillmorei'' in 1994, by Martin Lockley and Adrian Hunt. Lockley and Hunt suggested that it was very likely the track was made by a ''Tyrannosaurus rex'', which would make it the first known footprint from this species. The track was made in what was once a vegetated wetland mud flat. It measures 83&nbsp;centimeters (33&nbsp;in) long by 71&nbsp;cm (28&nbsp;in) wide.<ref name="lockley&hunt1994">Lockley. M. G., and Hunt, A. P. (1994). "A track of the giant theropod dinosaur ''Tyrannosaurus'' from close to the Cretaceous/Tertiary boundary, northern New Mexico." ''Ichnos'', '''3''': 213-218.</ref>

A second footprint that may have been made by a ''Tyrannosaurus'' was first reported in 2007 by British paleontologist Phil Manning, from the ] of ]. This second track measures 76&nbsp;cm (30&nbsp;in) long, shorter than the track described by Lockley and Hunt. Whether or not the track was made by ''Tyrannosaurus'' is unclear, though ''Tyrannosaurus'' and ''Nanotyrannus'' are the only large theropods known to have existed in the Hell Creek Formation. Further study of the track (a full description has not yet been published) will compare the Montana track with the one found in New Mexico.<ref name="rextrack2007">"T. rex footprint discovered?" The Natural History Museum, London. Accessed online December 18th, 2007 http://www.nhm.ac.uk/about-us/news/2007/october/news_12515.html</ref>

===Locomotion===
] footprints. No such sequence has yet been reported for tyrannosaurs, making gait and speed estimates difficult.]]
There are two main issues concerning the locomotory abilities of ''Tyrannosaurus'': how well it could turn; and what its maximum straight-line speed was likely to have been. Both are relevant to the debate about whether it was a hunter or a scavenger (see below).

''Tyrannosaurus'' may have been slow to turn, possibly taking one to two seconds to turn only 45° – an amount that humans, being vertically oriented and tail-less, can spin in a fraction of a second.<ref> Cosmos magazine</ref> The cause of the difficulty is ], since much of ''Tyrannosaurus''’ mass was some distance from its center of gravity (like a human carrying a heavy timber) - although it might have reduced the average distance by arching its back and tail and pulling its head and forelimbs close to its body (rather like the way an ice skater pulls his or her arms closer in order to spin faster).<ref name="CarrierWalterLee2000TurningPerformance">{{cite journal | authors=Carrier, D.R., Walter, R.M., and Lee, D.V. | title=Influence of rotational inertia on turning performance of theropod dinosaurs: clues from humans with increased rotational inertia | journal=Journal of Experimental Biology | issue=204 | pages=3917-3926 | date=2001 | publisher=The Company of Biologists Limited | url=http://jeb.biologists.org/cgi/content/full/204/22/3917
}}</ref>

Scientists have produced a wide range of maximum speed estimates, mostly around 11&nbsp;meters/second (25&nbsp;mph), but a few as low as 5-11&nbsp;meters/second (12-25&nbsp;mph), and a few as high as 20&nbsp;meters/second (45&nbsp;mph). Researchers have to rely on various estimating techniques because, while there are many ] of very large theropods walking, so far none have been found of very large theropods running - and this absence ''may'' indicate that they did not run.<ref>{{cite journal | author=Hutchinson, J.R. | title=Biomechanical Modeling and Sensitivity Analysis of Bipedal Running Ability. II. Extinct Taxa | journal=Journal of Morphology | volume=262 | issue=1 | pages=441–461 | date=2004 | url=http://www.rvc.ac.uk/AboutUs/Staff/jhutchinson/documents/JRH13.pdf}} Abstract also at
}}</ref> Scientists who think that ''Tyrannosaurus'' was able to run point out that hollow bones and other features that would have lightened its body may have kept adult weight to a mere 5&nbsp;tons or so, or that other animals like ]es and ]s with long, flexible legs are able to achieve high speeds through slower but longer strides. Additionally, some have argued that ''Tyrannosaurus'' had relatively larger leg muscles than any animal alive today, which could have enabled fast running (40&ndash;70&nbsp;km/h or 25&ndash;45&nbsp;mph).<ref name="dinocards7">Hajdul, R. (1997). Tendons. ''Dinosaur Cards''. Orbis Publishing Ltd. D36044311.</ref>

]
Jack Horner and Don Lessem argued in 1993 that ''Tyrannosaurus'' was slow and probably could not run (no airborne phase in mid-stride), because its ratio of femur (thigh bone) to tibia (shin bone) length was greater than 1, as in most large theropods and like a modern ].<ref name="hornerlessem1993" /> However, Holtz (1998) noted that tyrannosaurids and some closely related groups had significantly longer ] hindlimb components (shin plus foot plus toes) relative to the femur length than most other theropods), and that tyrannosaurids and their close relatives had a tightly interlocked ] that more effectively transmitted locomotory forces from the foot to the lower leg than in earlier theropods ("metatarsus" means the foot bones, which function as part of the leg in ] animals). He therefore concluded that tyrannosaurids and their close relatives were the fastest large theropods.<ref name="Holtz1998TaxonomyCoelurosauria">{{cite journal
| author=Holtz, T.R. | title=Phylogenetic taxonomy of the Coelurosauria (Dinosauria; Theropoda)
| journal=Journal of Paleontology | date=May 1996 | volume=70 | issue=3 | pages=536-538}}</ref>

Christiansen (1998) estimated that the leg bones of ''Tyrannosaurus'' were not significantly stronger than those of elephants, which are relatively limited in their top speed and never actually run (there is no airborne phase), and hence proposed that the dinosaur's maximum speed would have been about 11&nbsp;meters/second (about 24&nbsp;mph), which is about the speed of a human sprinter. But he also noted that such estimates depend on many dubious assumptions.<ref name="Christiansen1998Strength">{{cite journal
| author=Christiansen, P. | title=Strength indicator values of theropod long bones, with comments on limb proportions and cursorial potential | journal=Gaia | date=1998 | volume=15 | pages=241–255 |url=http://www.mnhn.ul.pt/geologia/gaia/19.pdf |format=pdf | issn=0871-5424}}</ref>

Farlow and colleagues (1995) have argued that a 6-8&nbsp;ton ''Tyrannosaurus'' would have been critically or even fatally injured if it had fallen while moving quickly, since its torso would have slammed into the ground at a deceleration of 6&nbsp;''g'' (six times the acceleration due to gravity, or about 60&nbsp;meters/s²) and its tiny arms could not have reduced the impact.<ref name="farlowetal1995"/><ref> New Scientist, ] ], p. 18.</ref> However, ]s have been known to gallop at 50&nbsp;km/h (31&nbsp;mph), despite the risk that they might break a leg or worse, which can be fatal even in a "safe" environment such as a zoo.<ref>{{cite web| url=http://www.wildlifesafari.info/giraffe.html| publisher=WildlifeSafari.info| title=Giraffe| accessdate = 2006-04-29}}</ref><ref>{{cite web| url=http://www.zoo.org/zoo_info/history/chapters/history4.html | title=The History of Woodland Park Zoo - Chapter 4| accessdate = 2006-04-29}}</ref> Thus it is quite possible that ''Tyrannosaurus'' also moved fast when necessary and had to accept such risks.<ref name="Alexander2006DinoBioMechanics">{{cite journal |author=Alexander, R.M. |title=Dinosaur biomechanics |journal=Proc Biol Sci. |date=August 7 2006 |volume=273 |issue=1596 | pages=1849–1855
|doi: 10.1098/rspb.2006.3532 |publisher=The Royal Society |url=http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1634776
| doi = 10.1098/rspb.2006.3532 <!--Retrieved from CrossRef by DOI bot-->
}}</ref><ref name="Hanna2002MultipleInjuriesBigAl">{{cite journal |last=Hanna |first=Rebecca R. |year=2002 |title=Multiple injury and infection in a sub-adult theropod dinosaur (''Allosaurus fragilis'') with comparisons to allosaur pathology in the Cleveland-Lloyd dinosaur quarry collection |journal=Journal of Vertebrate Paleontology |volume=22 |issue=1 |pages=76–90}} catalogs the injuries of the '']'' known as "]" - at least one was attributed to a fall.</ref>
]
Most recent research on ''Tyrannosaurus'' locomotion does not narrow down speeds further than a range from 17&nbsp;km/h (11&nbsp;mph) to 40&nbsp;km/h (25&nbsp;mph), i.e. from walking or slow running to moderate-speed running. For example, a 2002 paper in the journal '']'' used a mathematical model (validated by applying it to three living animals, ]s, ]s, and ]s; additionally later eight more species including emus and ostriches<ref>{{cite journal | author=Hutchinson, J.R. | title=Biomechanical Modeling and Sensitivity Analysis of Bipedal Running Ability. II. Extinct Taxa | journal=Journal of Morphology | volume=262 | issue=1 | pages=441–461 | date=2004 | url=http://www.rvc.ac.uk/AboutUs/Staff/jhutchinson/documents/JRH13.pdf}} Abstract also at }}</ref>) to gauge the leg muscle mass needed for fast running (over 40&nbsp;km/h ). They found that proposed top speeds in excess of 40&nbsp;km/h (25&nbsp;mph) were unfeasible, because they would require very large leg muscles (more than approximately 40&ndash;86%&nbsp;of total body mass.) Even moderately fast speeds would have required large leg muscles. This discussion is difficult to resolve, as it is unknown how large the leg muscles actually were in ''Tyrannosaurus''. If they were smaller, only 18&nbsp;km/h (~11&nbsp;mph) walking/jogging might have been possible.<ref name="HutchinsonGarcia2002TrexSlow">{{cite journal | authors=Hutchinson, J. R. and Garcia, M. | date=28 February 2002 | title=''Tyrannosaurus'' was not a fast runner | journal=Nature | volume=415 | pages=1018–1021 | doi=10.1038/4151018a | http://www.nature.com/nature/journal/v415/n6875/full/4151018a.html | author = Hutchinson, John R.}} Summary in press release </ref><ref name="dinocards7"/>

A study in 2007 used computer models to estimate running speeds, based on data taken directly from fossils, and claimed that ''T. rex'' had a top running speed of 8 meters per second (18&nbsp;mph). An average professional ] (soccer) player would be slightly slower, while a human sprinter can reach 12&nbsp;m/s (27&nbsp;mph). Note that these computer models predict a top speed of 17.8&nbsp;m/second (about 45&nbsp;mph) for a 3&nbsp;kilogram (7&nbsp;lb) '']''<ref name="SellersManning2007ProcRSocB"</ref>{{cite journal | authors=Sellers, W.I., and Manning, P.L. | title=Estimating dinosaur maximum running speeds using evolutionary robotics
| journal=Proc. R. Soc. B | doi:10.1098/rspb.2007.0846 | publisher=The Royal Society | date=July 2007 | url=http://dinonews.net/rubriq/articles.php5?action=open&ref=2007_sellers_speed}} This may be a preliminary version of Sellers, W. I., Manning, P.L., Crompton, R.H. and Codd, J.R., . (2007), "Exploring elastic energy storage effects in bipedal locomotion using evolutionary robotics", ''Journal of Biomechanics'', in-review</ref><ref>. ''BBC News'' website, Tuesday, ] ]. The article quotes Dr Bill Sellers, University of Manchester, co-author of a paper published in ''Proceedings of the Royal Society B''. Retrieved ] ].</ref> (probably a juvenile individual).<ref name=compysize>{{cite journal|last=Callison|first=G.|coauthors=H. M. Quimby|year=1984|title= Tiny dinosaurs: Are they fully grown? |journal=Journal of Vertebrate Paleontology|volume=3 |pages=200–209|doi=|url=}}</ref>

Those who argue that ''Tyrannosaurus'' was incapable of running estimate the top speed of ''Tyrannosaurus'' at about 17&nbsp;km/h (11&nbsp;mph). This is still faster than its most likely prey species, ]s and ]ns.<ref name="HutchinsonGarcia2002TrexSlow" /> In addition, some advocates of the idea that ''Tyrannosaurus'' was a predator (see below) claim that tyrannosaur running speed is not important, since it may have been slow but still faster than its probable prey.<ref name = "unearthingtrex-Traits">{{cite web | title=Unearthing T. rex: T. rex In-Depth: Traits (See above) | url=http://www.unearthingtrex.com/pages/rex_traits.html#weight | accessmonthday = December 11 | accessyear=2005 }}</ref> However, Paul and Christiansen (2000) argued that at least the later ceratopsians had upright forelimbs and the larger species may have been as fast as ].<ref name="PaulChristiansen2000NeoceratopsianForelimbPosture">{{ cite journal | authors=Paul, G.S., and Christiansen, P. | title=Forelimb posture in neoceratopsian dinosaurs: implications for gait and locomotion | journal=Paleobiology | volume=26 | issue=3 | date=September 2000 | url=http://www.bioone.org/perlserv/?request=get-document&doi=10.1666%2F0094-8373(2000)026%3C0450%3AFPINDI%3E2.0.CO%3B2 }}</ref> Healed ''Tyrannosaurus'' bite wounds on ceratopsian fossils are interpreted as evidence of attacks on living ceratopsians (see below). If the ceratopsians that lived alongside ''Tyrannosaurus'' were fast, that casts doubt on the argument that ''Tyrannosaurus'' did not have to be fast to catch its prey. Alternatively, perhaps ''Tyrannosaurus'' used ambush tactics to attack faster prey animals.<ref name="dinocards7"/> The debate about ''Tyrannosaurus''’ speed seems far from finished.

===Feeding strategies===
]
The debate about whether ''Tyrannosaurus'' was a ] or a pure ] is as old as the debate about its locomotion. Lambe (1917) described a good skeleton of ''Tyrannosaurus''’ close relative '']'' and concluded that it and therefore also ''Tyrannosaurus'' was a pure scavenger, because the ''Gorgosaurus''’ teeth showed hardly any wear.<ref name="Lambe1917Gorgosaurus">{{ cite journal
| author=Lambe, L. B. | date=1917 | title=The Cretaceous theropodous dinosaur ''Gorgosaurus'' | journal=Memoirs of the Geological Survey of Canada | volume=100 | pages=1-84 }}</ref> This argument is no longer taken seriously, because theropods replaced their teeth quite rapidly. Ever since the first discovery of ''Tyrannosaurus'' most scientists have agreed that it was a predator, although like modern large predators it would have been happy to scavenge or steal another predator's kill if it had the opportunity.<ref name="FarlowHoltz2002FossilRecordPredation">{{Citation | authors=Farlow, J. O. and Holtz, T. R. | contribution=The fossil record of predation in dinosaurs | editors=Kowalewski, M. and Kelley, P.H | title=The Fossil Record of Predation | date=2002
| series=The Paleontological Society Papers | volume=8 | pages=251–266 | url=http://www.yale.edu/ypmip/predation/Chapter_09.pdf |format=pdf}}</ref><ref name="dinocards2">Dorey, M. (1997). Tyrannosaurus. ''Dinosaur Cards''. Orbis Publishing Ltd. D36045907.</ref>

Noted ] expert ] is currently the major advocate of the idea that ''Tyrannosaurus'' was exclusively a scavenger and did not engage in active hunting at all.<ref name="Horner1994SteakKnives">{{ cite journal | author=Horner, J.R.
| date=1994 | title=Steak knives, beady eyes, and tiny little arms (a portrait of ''Tyrannosaurus'' as a scavenger) | journal=The Paleontological Society Special Publication | volume=7 | pages=157–164}}</ref><ref name="hornerlessem1993" /<ref><ref name="BBC2003TrexOnTrial"{{ cite web | url=http://news.bbc.co.uk/1/hi/sci/tech/3112527.stm | title=T. rex goes on trial | author=Amos, J.
| publisher=BBC | date=31 July 2003}}</ref> Horner has presented several arguments to support the pure scavenger hypothesis:
], ].]]
* Tyrannosaurs had large ]s and ]s (relative to their brain size). These suggest a highly developed sense of smell which could sniff out carcasses over great distances, as modern ]s do. Opponents of the pure scavenger hypothesis have used the example of vultures in the opposite way, arguing that the scavenger hypothesis is implausible because the only modern pure scavengers are large gliding birds, which use their keen senses and energy-efficient gliding to cover vast areas economically.<ref name="OnlyModernScavengersBirds">e.g. {{ cite book | author=Paul, G.S. | title=Predatory Dinosaurs of the World | date=1988 | publisher=Simon and Schuster}}</ref> However, researchers from ] concluded that an ecosystem as productive as the current ] would provide sufficient ] for a large theropod scavenger, although the theropod might have had to be cold-blooded in order to get more ] from carrion than it spent on foraging (see ]). They also suggested that modern ecosystems like Serengeti have no large terrestrial scavengers because gliding birds now do the job much more efficiently, while large theropods did not face competition for the scavenger ] from gliding birds.<ref name="RuxtonHouston2003TRexScavenger">{{ cite journal | title=Could ''Tyrannosaurus rex'' Have Been a Scavenger Rather than a Predator? An Energetics Approach | authors=Ruxton, G.D, and Houston, D.C. | Proceedings: Biological Sciences | publisher=The Royal Society | volume=270 | issue=1516 | date=Apr. 7 2003 | pages=731-733 | doi=10.1098/rspb.2002.2279.
}} Press releases and summaries at and </ref>
* Tyrannosaur teeth could crush bone, and therefore could extract as much food (]) as possible from carcass remnants, usually the least nutritious parts. Karen Chin and colleagues have found bone fragments in ]s (fossilized dung) that they attribute to tyrannosaurs, but point out that a tyrannosaur's teeth were not well adapted to systematically chewing bone like ]s do to extract marrow.<ref name="ChinEtal1998KingSizeCoprolite">{{ cite journal | authors=Chin, K., Erickson, G.M. ''et al'' | date=June 18 1998 | title=A king-sized theropod coprolite | journal=Nature | volume=393 | pages=680}} Summary at {{ cite journal | author=Monastersky, R.
| title=Getting the scoop from the poop of ''T. rex'' | journal=Science News | volume=153
| issue=25 | date=June 20 1998 | pages=391 |url=http://www.sciencenews.org/pages/sn_arc98/6_20_98/fob2.htm | doi = 10.2307/4010364 <!--Retrieved from CrossRef by DOI bot-->
}}</ref>
* Since at least some of ''Tyrannosaurus'''s potential prey could move quickly, evidence that it walked instead of ran could indicate that it was a scavenger.<ref name="Horner1994SteakKnives" /><ref name="dinodictionary">Walters, M., Paker, J. (1995). Dictionary of Prehistoric Life. Claremont Books. ISBN 1-85471-648-4.</ref> On the other hand, recent analyses suggest that ''Tyrannosaurus'', while slower than large modern terrestrial predators, may well have been fast enough to prey on large ] and ].<ref name="HutchinsonGarcia2002TrexSlow" /><ref name = "unearthingtrex-Traits"/> It may also have used ambush tactics to attack faster prey animals.<ref name="dinocards7"/>
]. ]]
Other evidence suggests hunting behavior in ''Tyrannosaurus''. Stevens (2006) found that the eye-sockets of tyrannosaurs are positioned so that the eyes would point forward, giving them ] slightly better than that of modern ]s. He also pointed out that the tyrannosaur lineage had a history of steadily improving binocular vision. It is hard to see how ] would have favored this long-term trend if tyrannosaurs had been pure scavengers, which would not have needed the advanced ] that ] provides.<ref name="Stevens2006Binocular">{{ cite journal | author=Stevens, K.A. | date=2006 | title=Binocular vision in theropod dinosaurs | journal=Journal of Vertebrate Paleontology | volune=26 | pages=321-330 |url=http://www.bioone.org/perlserv/?request=get-document&doi=10.1671%2F0272-4634(2006)26%5B321%3ABVITD%5D2.0.CO%3B2
| volume = 26
| doi = 10.1671/0272-4634(2006)26%5B321:BVITD%5D2.0.CO;2
| doilabel = 10.1671/0272-4634(2006)262.0.CO;2 <!--Retrieved from CrossRef by DOI bot-->
}} and copy at Also (press release) has a good picture of a ''T rex'' skull</ref> In modern animals, binocular vision is found mainly in predators (the principal exceptions are ]s, which need it for leaping from branch to branch).

At the site where the very large tyrannosaur named ] was found, a skeleton of the hadrosaurid '']'' was also found, with healed tyrannosaur-inflicted damage on its tail ]e. The fact that the damage seem to have healed suggests that the ''Edmontosaurus'' survived a tyrannosaur's attack on a living target, i.e. the tyrannosaur had attempted active predation.<ref name="erickson1996">Erickson, G. M., and Olson, K. H. (1996). "Bite marks attributable to ''Tyrannosaurus rex'': preliminary description and implications." ''Journal of Vertebrate Paleontology'', '''16'''(1): 175–178.</ref><ref name=carpenter1998>{{cite journal |last=Carpenter |first=K. |authorlink=Kenneth Carpenter |year=1998 |title=Evidence of predatory behavior by theropod dinosaurs. |journal=Gaia |volume=15 |pages=135–144 |url=http://vertpaleo.org/publications/jvp/15-576-591.cfm|accessdate=2007-12-05}}</ref> A '']'' was found in Mexico found with bite marks on its ]. These were also inflicted by a tyrannosaur and they too appear healed, indicating active predation by the tyrannosaur.<ref name="fowler2006">Fowler, D. W., and Sullivan, R. M. (2006). "A ceratopsid pelvis with toothmarks from the Upper Cretaceous Kirtland Formation, New Mexico: evidence of late Campanian tyrannosaurid feeding behavior." ''New Mexico Museum of Natural History and Science Bulletin'', '''35''': 127–130.</ref>

When examining ], paleontologist ] found a broken and healed ] and tail vertebrae, scarred facial bones and a tooth from another ''Tyrannosaurus'' embedded in a neck vertebra. If correct, these might be strong evidence for aggressive behavior between tyrannosaurs but whether it would be competition for food and mates or active ] is unclear.<ref name=TC98>{{cite journal |last=Tanke |first=Darren H. |authorlink=Darren Tanke |coauthors=and Currie, Philip J. |year=1998 |title=Head-biting behavior in theropod dinosaurs: paleopathological evidence |journal=Gaia |issue=15 |pages=167–184 |url=http://www.mnhn.ul.pt/geologia/gaia/12.pdf |issn=0871-5424 |format=pdf}}</ref> However, further recent investigation of these purported wounds has shown that most are infections rather than injuries (or simply damage to the fossil after death) and the few injuries are too general to be indicative of intraspecific conflict.<ref name="dinocards5">Goldstone, E. (1997). Injury & Disease, Part 3. ''Dinosaur Cards''. Orbis Publishing Ltd. D36045009.</ref>

Some researchers argue that if ''Tyrannosaurus'' were a scavenger, another dinosaur had to be the top predator in the Amerasian Upper Cretaceous. Top prey were the larger ]ns and ]s. The other tyrannosaurids share so many characteristics that only small ] remain as feasible top predators. In this light, scavenger hypothesis adherents have suggested that the size and power of tyrannosaurs allowed them to ] from smaller predators.<ref name="dinodictionary">Walters, M., Paker, J. (1995). Dictionary of Prehistoric Life. Claremont Books. ISBN 1-85471-648-4.</ref>

==History==
], president of the ], named ''Tyrannosaurus rex'' in 1905. The generic name is derived from the ] words ''τυραννος'' (''tyrannos'', meaning "tyrant") and ''σαυρος'' (''sauros'', meaning "lizard"). Osborn used the ] word ''rex'', meaning "king", for the specific name. The full ] therefore translates to "tyrant lizard king," emphasizing the animal's size and perceived dominance over other species of the time.<ref name="osborn1905"/>

=== Earliest finds ===
] by ].]]
The vertebrae named ''Manospondylus'' by Cope in 1892 can be considered the first known specimen of ''Tyrannosaurus rex''. ], assistant curator of the ], found the second ''Tyrannosaurus'' skeleton in ] in 1900. This specimen was originally named ''Dynamosaurus imperiosus'' in the same paper in which ''Tyrannosaurus rex'' was described.<ref>Osborn, H. F. 1905.''Tyrannosaurus'' and other Cretaceous carnivorous dinosaurs. ''Bulletin of the American Museum of Natural History'' 21;259–265</ref> Had it not been for page order, ''Dynamosaurus'' would have become the official name. The original "''Dynamosaurus''" material resides in the collections of the ], ].<ref name="dinocards10">White, S. (1997). Tyrannosaurus. ''Dinosaur Cards''. Orbis Publishing Ltd. D36046009.</ref>

In total, Barnum Brown found five ''Tyrannosaurus'' partial skeletons. Brown collected his second ''Tyrannosaurus'' in 1902 and 1905 in ], ]. This is the ] used to describe ''Tyrannosaurus rex'' ], 1905. In 1941 it was sold to the ] in ], ]. Brown's fourth and largest find, also from Hell Creek, is on display in the ] in ].<ref name="hornerlessem1993">Horner, J.R. & Lessem, D. 1993. ''The Complete T. rex: How Stunning New Discoveries Are Changing Our Understanding of the World's Most Famous Dinosaur''. New York: Simon & Schuster. 235pp.</ref>

Although there are numerous skeletons in the world, only one track has been documented — at ] in northeast ]. It was discovered in 1983 and identified and documented in 1994.<ref></ref>

=== Notable specimens ===
{{Main|Specimens of Tyrannosaurus}}
], Chicago, showing the forelimbs. The ']' is between the forelimbs.]]
], ] paleontologist, discovered the most complete (more than 90%) and, until 2001 the largest, ''Tyrannosaurus'' fossil skeleton known in the ] near ], on ], ]. This ''Tyrannosaurus'', nicknamed "Sue" in her honor, was the object of a legal battle over its ownership. In 1997 this was settled in favor of Maurice Williams, the original land owner, and the fossil collection was sold at auction for ] 7.6 million, making it the most expensive dinosaur skeleton to date. It has now been reassembled and is currently exhibited at the ]. A study of this specimen's fossilized bones showed that "Sue" reached full size at age 19 and died at age 28, the longest any tyrannosaur is known to have lived.<ref name="Stokstad2004TRExGrowthSpurt">{{ cite journal
| author=Stokstad, E.
| title=Bone Study Shows ''T. rex'' Bulked Up With Massive Growth Spurt
| journal=Science
| date=13 August 2004
| volume=305
| issue=5686
| pages= 930 - 931
| doi= 10.1126/science.305.5686.930a
| url=http://www.sciencemag.org/cgi/content/summary/305/5686/930a
}}</ref> The "Sue" specimen apparently died from a massive bite to the head, which could only have been inflicted by another tyrannosaur.<ref name="Brochu2003">{{cite journal
| title=Lessons From A Tyrannosaur: The Ambassadorial Role Of Paleontology
| author=Brochui, C.A.
| journal=Palaios
| volume=18
| issue=6
| date=December 2003
| url=http://www.bioone.org/perlserv/?request=get-document&doi=10.1669%2F0883-1351(2003)018%3C0475%3ALFATTA%3E2.0.CO%3B2
| doi=10.1669/0883-1351(2003)018<0475:LFATTA>2.0.CO;2
| pages = 475
}}</ref> Researchers reported that a subadult and a juvenile skeleton were found in the same quarry as the "Sue" specimen, which has been used to support the hypothesis that tyrannosaurs may have lived in social groups of some kind.<ref name="sue"> Guinness World Records Ltd. (2003). ''2003 Guinness World Records''. pg 90.</ref>

Another ''Tyrannosaurus'', nicknamed "Stan", in honor of amateur paleontologist Stan Sacrison, was found in the Hell Creek Formation near ], in the spring of 1987. After 30,000 hours of digging and preparing, a 65% complete skeleton emerged. Stan is currently on display in the Black Hills Museum of Natural History Exhibit in ], after an extensive world tour. This tyrannosaur, too, was found to have many bone pathologies, including broken and healed ribs, a broken (and healed) neck and a spectacular hole in the back of its head, about the size of a ''Tyrannosaurus'' tooth. Both Stan and Sue were examined by Peter Larson.
]
In 2001, a 50% complete skeleton of a juvenile ''Tyrannosaurus'' was discovered in the Hell Creek Formation in Montana, by a crew from the ] of ], ]. Dubbed "]," the find was initially considered the first known skeleton of the pygmy tyrannosaurid '']'' but subsequent research has revealed that it is more likely a juvenile ''Tyrannosaurus''.<ref> Currie, P. J., Hurum, J. H., and Sabath, K. 2003. . Acta Palaeontologica Polonica 48: 227–234</ref> It is the most complete and best preserved juvenile example known to date. Jane has been examined by ], ], ], ] and several other renowned ]s, because of the uniqueness of her age. Jane is currently on exhibit at the Burpee Museum of Natural History in Rockford, Illinois.<ref name="dinocards9">Croucher, B. (1997). Beast of the Badlands. ''Dinosaur Cards''. Orbis Publishing Ltd. D36045407.</ref><ref name="visitjane"></ref>

Also in 2001, Dr. Jack Horner discovered a specimen of ''T. rex'' around 10% larger than "Sue". Dubbed ''C. rex'' (or "Celeste" after Jack's wife), this specimen is currently under study.

In a press release on ], ], Montana State University revealed that it possessed the largest ''Tyrannosaurus'' skull yet discovered. Discovered in the 1960s and only recently reconstructed, the skull measures 59&nbsp;inches (150&nbsp;cm) long compared to the 55.4&nbsp;inches (141&nbsp;cm) of “Sue’s” skull, a difference of 6.5%.<ref>{{cite web | title=Museum unveils world's largest ''T-rex'' skull. | url=http://www.montana.edu/cpa/news/nwview.php?article=3607 | accessmonthday = April 7 | accessyear= 2006}}</ref><ref>{{cite web | title= New Biggest ''T-rex'' Skull.
| url=http://palaeoblog.blogspot.com/2006/04/new-biggest-t-rex-skull.html
| author= Ryan, M. J | accessmonthday = April 12 | accessyear= 2006}}</ref>

==Appearances in popular culture==
{{Main|Cultural depictions of Tyrannosaurus}}
]
Since it was first described in 1905, ''Tyrannosaurus rex'' has become the most widely-recognized dinosaur in ]. It is the only dinosaur which is routinely referred to by its full scientific name (''Tyrannosaurus rex'') among the general public, and the scientific abbreviation ''T. rex'' has also come into wide usage (commonly misspelled "T-Rex").<ref name="brochu2003"/> ] notes this in '']'' and explains that a name like "''Tyrannosaurus rex'' is just irresistible to the tongue."<ref name="bakker1986"/>

Museum exhibits featuring ''T. rex'' are very popular; an estimated 10,000 visitors flocked to Chicago's Field Museum on the opening day of its "Sue" exhibit in 2003.<ref name="suerecord"> Guinness World Records Ltd. 2003. ''2003 Guinness World Records''. p. 90.</ref> ''T. rex'' has appeared numerous times on ] and in ]s, notably (in chronological order) '']'', '']'', '']'', '']'', '']'', '']'', '']'', and '']''. A number of books and ]s, including '']'', have also featured ''Tyrannosaurus'', which is typically portrayed as the biggest and most terrifying carnivore of all. At least one musical group, the band ], is named after the species. ''Tyrannosaurus''-related ]s, including numerous ]s and other merchandise, remain popular. Various businesses have capitalized on the popularity of ''Tyrannosaurus rex'' by using it in ].

==References==
{{reflist|2}}
<!-- Dead note "www.visitjane.com.450": {{cite web | title=Jane lives! | url=http://www.visitjane.com/ | accessmonthday=December 11 | accessyear=2005 }} -->

==See also==
* {{cite journal
| authors=Farlow, J.O., Gatesy, S.M., Holtz Jr., T.R., Hutchinson, J.R., and Robinson, J.M.
| title=Theropod Locomotion
| journal=American Zoologist
| volume=40
| issue=4
| pages=640-663
| date=2000
| publisher=The Society for Integrative and Comparative Biology
| url=http://icb.oxfordjournals.org/cgi/content/full/40/4/640
| doi=10.1093/icb/40.4.640
| author = Farlow, J. O.
}} - a good survey of research

==External links==
{{commons|Tyrannosaurus}}
{{wikispecies|Tyrannosaurus}}
{{wikibooks|Wikijunior Dinosaurs/T-Rex}}
{{portalpar|Dinosaurs}}
* "Tree of Life" page, very comprehensive survey by major authority Tom Holtz.
* {{cite news | url=http://www.guardian.co.uk/uk_news/story/0,3604,1281338,00.html | title=The secret of ''T. rex'''s colossal size: a teenage growth spurt | publisher=The Guardian | date=] ] }}
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* "Tree of Life" page, very comprehensive survey by major authority Tom Holtz.
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Revision as of 19:14, 4 May 2008

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