Editing Tyrannosaurus (section)

===Skull===
[[File:Tyrannosaurus rex AMNH 5027 skull.png|thumb|Skull of specimen AMNH 5027 with labelled diagrams in dorsal, lateral, anterior, posterior, and medial (lower jaw) views]]
The largest known ''T. rex'' skulls measure up to {{cvt|1.54|m|ft}} in length.<ref name="MOR008" /><ref name="SueFMNH" /> Large [[Fenestra (anatomy)|fenestrae]] (openings) in the skull reduced weight, as in all carnivorous theropods. In other respects ''Tyrannosaurus''<nowiki>'</nowiki>s skull was significantly different from those of large non-[[tyrannosaurid]] theropods. It was extremely wide at the rear but had a narrow snout, allowing unusually good [[binocular vision]].<ref name="Stevens2006Binocular">{{Cite journal|last=Stevens |first=Kent A. |date=June 2006 |title=Binocular vision in theropod dinosaurs |journal=Journal of Vertebrate Paleontology |issue=2 |pages=321–330 |volume=26 |doi=10.1671/0272-4634(2006)26[321:BVITD]2.0.CO;2|s2cid=85694979 }}</ref><ref name="jaffe">{{Cite journal |last=Jaffe |first=E. |date=July 1, 2006 |title=Sight for 'Saur Eyes: ''T. rex'' vision was among nature's best |url=http://www.sciencenews.org/view/generic/id/7500/title/Sight_for_Saur_Eyes_%3Ci%3ET._rex%3Ci%3E_vision_was_among_natures_best |journal=[[Science News]] |volume=170 |issue=1 |pages=3–4 |doi=10.2307/4017288 |jstor=4017288 |access-date=October 6, 2008 |archive-date=September 29, 2012 |archive-url=https://web.archive.org/web/20120929190336/http://www.sciencenews.org/view/generic/id/7500/title/Sight_for_Saur_Eyes_%3Ci%3ET._rex%3Ci%3E_vision_was_among_natures_best  }}</ref> The skull bones were massive and the [[nasal bone|nasals]] and some other bones were fused, preventing movement between them; but many were [[Pneumatized bones|pneumatized]] (contained a "honeycomb" of tiny air spaces) and thus lighter. These and other skull-strengthening features are part of the [[tyrannosaurid]] trend towards an increasingly powerful bite, which easily surpassed that of all non-tyrannosaurids.<ref name="SnivelyHendersonPhillips2006FusedVaultedNasals">{{Cite journal |last1=Snively |first1=E. |last2=Henderson |first2=D. M. |last3=Phillips |first3=D. S. |year=2006 |title=Fused and vaulted nasals of tyrannosaurid dinosaurs: Implications for cranial strength and feeding mechanics |url=http://www.app.pan.pl/archive/published/app51/app51-435.pdf |journal=Acta Palaeontologica Polonica |volume=51 |issue=3 |pages=435–454 |access-date=October 8, 2008 |archive-date=August 19, 2018 |archive-url=https://web.archive.org/web/20180819045612/http://www.app.pan.pl/archive/published/app51/app51-435.pdf |url-status=live }}</ref><ref name="MM03">{{Cite journal |last=Meers |first=M. B. |s2cid=86782853 |date=August 2003 |title=Maximum bite force and prey size of ''Tyrannosaurus rex'' and their relationships to the inference of feeding behavior |journal=Historical Biology |volume=16 |issue=1 |pages=1–12 |doi=10.1080/0891296021000050755}}</ref><ref name="GEetal96">{{Cite journal |last1=Erickson |first1=G. M. |last2=Van Kirk |first2=S. D. |last3=Su |first3=J. |last4=Levenston |first4=M. E. |last5=Caler |first5=W. E. |last6=Carter |first6=D. R. |s2cid=4325859 |year=1996 |title=Bite-force estimation for ''Tyrannosaurus rex'' from tooth-marked bones |journal=Nature |volume=382 |issue=6593 |pages=706–708 |bibcode=1996Natur.382..706E |doi=10.1038/382706a0 |url=https://zenodo.org/record/3730962 |archive-date=July 4, 2020 |access-date=July 4, 2020 |archive-url=https://web.archive.org/web/20200704181008/https://zenodo.org/record/3730962 |url-status=live }}</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" />

The teeth of ''T. rex'' displayed marked [[heterodont]]y (differences in shape).<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 |doi=10.2307/3889334 |jstor=3889334}}</ref><ref name="Smith2005HeterodontyTRex">{{Cite journal |last=Smith |first=J. B. |date=December 1, 2005 |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 |doi=10.1671/0272-4634(2005)025[0865:HITRIF]2.0.CO;2|s2cid=86184190 }}</ref> The [[premaxilla]]ry teeth, four per side at the front of the upper jaw, were closely packed, ''D''-shaped in cross-section, had reinforcing ridges on the rear surface, were [[Incisor|incisiform]] (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 name="New Scientist1998DinosaurDetectives">{{Cite magazine |last1=Douglas |first1=K. |last2=Young |first2=S. |year=1998 |title=The dinosaur detectives |url=https://www.newscientist.com/channel/life/dinosaurs/mg15821305.300 |magazine=[[New Scientist]] |access-date=October 16, 2008 |quote=One palaeontologist memorably described the huge, curved teeth of T. rex as 'lethal bananas' |archive-date=May 17, 2008 |archive-url=https://web.archive.org/web/20080517160559/http://www.newscientist.com/channel/life/dinosaurs/mg15821305.300 |url-status=live }}</ref> Those in the upper jaw, twelve per side in mature individuals,<ref name="brochu2003" /> were larger than their counterparts of the lower jaw, except at the rear. The largest found so far is estimated to have been {{cvt|30.5|cm}} long including the root when the animal was alive, making it the largest tooth of any carnivorous dinosaur yet found.<ref name="SueFMNH2">{{Cite web |url=http://www.fieldmuseum.org/sue/about_vital.asp |title=Sue's vital statistics |website=Sue at the Field Museum |publisher=[[Field Museum of Natural History]] |archive-url=https://web.archive.org/web/20070929090231/http://www.fieldmuseum.org/SUE/about_vital.asp <!--Added by H3llBot--> |archive-date=September 29, 2007 |access-date=September 15, 2007}}</ref> The lower jaw was robust. Its front [[dentary bone]] bore thirteen teeth. Behind the tooth row, the lower jaw became notably taller.<ref name="brochu2003" /> The upper and lower jaws of ''Tyrannosaurus'', like those of many dinosaurs, possessed numerous [[Foramen|foramina]], or small holes in the bone. Various functions have been proposed for these foramina, such as a crocodile-like sensory system<ref name="carr2017" /> or evidence of [[Integument|extra-oral structures]] such as scales or potentially lips,<ref>{{Cite thesis|last=Morhardt|first=Ashley|year=2009|title=Dinosaur smiles: Do the texture and morphology of the premaxilla, maxilla, and dentary bones of sauropsids provide osteological correlates for inferring extra-oral structures reliably in dinosaurs?|url=https://www.academia.edu/3871353|publisher=Western Illinois University|type=MSc thesis|archive-date=February 10, 2022|access-date=May 10, 2020|archive-url=https://web.archive.org/web/20220210063525/https://www.academia.edu/3871353|url-status=live}}</ref><ref name=":0" /><ref>{{cite book |title=MORPHOLOGY, TAXONOMY, AND PHYLOGENETIC RELATIONSHIPS OF THE MONTEVIALE CROCODYLIANS (OLIGOCENE, ITALY). |date=2018 |page=67 |url=https://scholar.google.com/scholar?hl=en&as_sdt=0%2C14&as_ylo=2018&as_yhi=2018&q=MORPHOLOGY%2C+TAXONOMY%2C+AND+PHYLOGENETIC+RELATIONSHIPS+OF+THE+MONTEVIALE+CROCODYLIANS+%28OLIGOCENE%2C+ITALY%29.&btnG= |access-date=October 9, 2020 |archive-date=February 10, 2022 |archive-url=https://web.archive.org/web/20220210114154/https://scholar.google.com/scholar?hl=en&as_sdt=0%2C14&as_ylo=2018&as_yhi=2018&q=MORPHOLOGY%2C+TAXONOMY%2C+AND+PHYLOGENETIC+RELATIONSHIPS+OF+THE+MONTEVIALE+CROCODYLIANS+%28OLIGOCENE%2C+ITALY%29.&btnG= |url-status=live }}</ref> with subsequent research on theropod tooth wear patterns supporting such a proposition.<ref name=CullenEtAl23>{{Cite journal |last1=Cullen |first1=Thomas M. |last2=Larson |first2=Derek W. |last3=Witton |first3=Mark P. |last4=Scott |first4=Diane |last5=Maho |first5=Tea |last6=Brink |first6=Kirstin S. |last7=Evans |first7=David C. |last8=Reisz |first8=Robert |date=March 31, 2023 |title=Theropod dinosaur facial reconstruction and the importance of soft tissues in paleobiology |journal=Science |language=en |volume=379 |issue=6639 |pages=1348–1352 |doi=10.1126/science.abo7877 |pmid=36996202 |bibcode=2023Sci...379.1348C |s2cid=257836765 |issn=0036-8075|doi-access=free }}</ref>