Editing Tyrannosaurus (section)

=== Brain and senses ===
[[File:Sue TRex Skull Full Frontal.JPG|thumb|upright|left|The eye-sockets faced mainly forwards, giving it good [[binocular vision]] ([[Sue specimen]]).]]
A study conducted by [[Lawrence Witmer]] and Ryan Ridgely of Ohio University found that ''Tyrannosaurus'' shared the heightened sensory abilities of other [[coelurosaur]]s, highlighting relatively rapid and coordinated eye and head movements; an enhanced ability to sense low frequency sounds, which would allow tyrannosaurs to track prey movements from long distances; and an enhanced sense of smell.<ref name="witmer2009">{{Cite journal |last1=Witmer |first1=L. M. |last2=Ridgely |first2=R. C. |date=2009 |title=New Insights into the Brain, Braincase, and Ear Region of Tyrannosaurs (Dinosauria, Theropoda), with Implications for Sensory Organization and Behavior |journal=The Anatomical Record |volume=292 |issue=9 |pages=1266–1296 |doi=10.1002/ar.20983 |pmid=19711459|s2cid=17978731 |doi-access=free }}</ref> A study published by Kent Stevens concluded that ''Tyrannosaurus'' had keen vision. By applying modified [[perimetry]] to facial reconstructions of several dinosaurs including ''Tyrannosaurus'', the study found that ''Tyrannosaurus'' had a binocular range of 55 degrees, surpassing that of modern hawks. Stevens estimated that ''Tyrannosaurus'' had 13 times the visual acuity of a human and surpassed the visual acuity of an eagle, which is 3.6 times that of a person. Stevens estimated a limiting far point (that is, the distance at which an object can be seen as separate from the horizon) as far as {{convert|6|km|mi|sp=us|abbr=on}} away, which is greater than the {{convert|1.6|km|mi|0|sp=us|abbr=on}} that a human can see.<ref name="Stevens2006Binocular"/><ref name="jaffe" /><ref name="stevenswebpage">{{Cite web |url=http://ix.cs.uoregon.edu/~kent/paleontology/binocularVision/ |title=The Binocular Vision of Theropod Dinosaurs |last=Stevens |first=K. A. |date=April 1, 2011 |access-date=July 19, 2013 |archive-date=August 19, 2018 |archive-url=https://web.archive.org/web/20180819050655/http://ix.cs.uoregon.edu/~kent/paleontology/binocularVision/ |url-status=live }}</ref>

Thomas Holtz Jr. would note that high depth perception of ''Tyrannosaurus'' may have been due to the prey it had to hunt, noting that it had to hunt ceratopsians such as ''[[Triceratops]]'', ankylosaurs such as ''[[Ankylosaurus]]'', and hadrosaurs. He would suggest that this made precision more crucial for ''Tyrannosaurus'' enabling it to, "get in, get that blow in and take it down." In contrast, ''[[Acrocanthosaurus]]'' had limited depth perception because they hunted large sauropods, which were relatively rare during the time of ''Tyrannosaurus''.<ref name="HoltzLecture2013" />

Though no ''Tyrannosaurus'' [[Scleral Ring|sclerotic ring]] has been found, [[Kenneth Carpenter]] estimated its size based on that of ''Gorgosaurus''. The inferred sclerotic ring for the [[Stan (dinosaur)|Stan specimen]] is ~{{convert|7|cm|in|abbr=on|sp=us}} in diameter with an internal aperture diameter of ~{{convert|3.5|cm|in|abbr=on|sp=us}}. Based on eye proportions in living reptiles, this implies a pupil diameter of about {{convert|2.5|cm|in|abbr=on|sp=us}}, an iris diameter about that of the sclerotic ring, and an eyeball diameter of {{convert|11-12|cm|in|abbr=on|sp=us}}. Carpenter also estimated an eyeball depth of ~{{convert|7.7-9.6|cm|in|abbr=on|sp=us}}. Based on these calculations, the [[f-number]] for Stan's eye is 3–3.8; since [[Diurnality|diurnal]] animals have f-numbers of 2.1 or higher, this would indicate that ''Tyrannosaurus'' had poor low-light vision and hunted during the day.<ref name="Trexpaleobiologychapter14">{{cite book|author=Carpenter, K.|chapter=A Closer Look at the Scavenging versus Predation by ''Tyrannosaurus rex''|title=Tyrannosaurid Paleobiology |year=2013 |publisher=Indiana University Press |isbn=978-0-253-00930-2 |editor-last=Parrish |editor-first=M. J. |editor-last2=Molnar |editor-first2=R. E. |editor-last3=Currie |editor-first3=P. J. |editor-last4=Koppelhus |editor-first4=E. B. |series=Life of the Past |location=Bloomington (Ind.) |pages=265–278 }}</ref>

''Tyrannosaurus'' had very large [[olfactory bulb]]s and [[olfactory nerve]]s relative to their brain size, the organs responsible for a heightened sense of smell. This suggests that the sense of smell was highly developed, and implies that tyrannosaurs could detect carcasses by scent alone across great distances. The sense of smell in tyrannosaurs may have been comparable to modern [[vulture]]s, which use scent to track carcasses for scavenging. Research on the olfactory bulbs has shown that ''T. rex'' had the most highly developed sense of smell of 21 sampled non-avian dinosaur species.<ref name="Calgary Herald">{{cite news |url=http://www.canada.com/calgaryherald/story.html?id=3641f27e-ca2e-44e8-a56b-f9a0b4aef4b5 |title=''T. Rex'' brain study reveals a refined 'nose' |date=October 28, 2008 |newspaper=Calgary Herald |access-date=October 29, 2008 |archive-date=December 6, 2008 |archive-url=https://web.archive.org/web/20081206065850/http://www.canada.com/calgaryherald/story.html?id=3641f27e-ca2e-44e8-a56b-f9a0b4aef4b5 |url-status=live }}</ref>
[[File:Tyrannosaurus brain aus.jpg|thumb|Cast of the braincase at the [[Australian Museum]], Sydney.]]
Somewhat unusually among theropods, ''T.&nbsp;rex'' had a very long [[cochlea]]. The length of the cochlea is often related to hearing acuity, or at least the importance of hearing in behavior, implying that hearing was a particularly important sense to tyrannosaurs. Specifically, data suggests that ''T. rex'' heard best in the low-frequency range, and that low-frequency sounds were an important part of tyrannosaur behavior.<ref name="witmer2009" /> A 2017 study by Thomas Carr and colleagues found that the snout of tyrannosaurids was highly sensitive, based on a high number of small openings in the facial bones of the related ''Daspletosaurus'' that contained [[sensory neuron]]s. The study speculated that tyrannosaurs might have used their sensitive snouts to measure the temperature of their nests and to gently pick up eggs and hatchlings, as seen in modern crocodylians.<ref name="carr2017" /> 
Another study published in 2021 further suggests that ''Tyrannosaurus'' had an acute sense of touch, based on neurovascular canals in the front of its jaws, which it could utilize to better detect and consume prey. The study, published by Kawabe and Hittori et al., suggests that ''Tyrannosaurus'' could also accurately sense slight differences in material and movement, allowing it to utilize different feeding strategies on different parts of its prey's carcasses depending on the situation. The sensitive neurovascular canals of ''Tyrannosaurus'' also likely were adapted to performing fine movements and behaviors such as nest building, parental care, and other social behavior such as intraspecific communication. The results of this study also align with results made in studying the related tyrannosaurid ''[[Daspletosaurus horneri]]'' and the [[allosauroid]] ''[[Neovenator]]'', which have similar neurovascular adaptations, suggesting that the faces of theropods were highly sensitive to pressure and touch.<ref>{{Cite journal|doi=10.1080/08912963.2021.1965137|title=Complex neurovascular system in the dentary of Tyrannosaurus|year=2021|last1=Kawabe|first1=Soichiro|last2=Hattori|first2=Soki|journal=Historical Biology|volume=34 |issue=7 |pages=1137–1145|doi-access=free|bibcode=2022HBio...34.1137K }}</ref><ref>{{Cite web|url=https://phys.org/news/2021-08-rex-jaw-sensors-fearsome-predator.html|title=T. rex's jaw had sensors that made it an even more fearsome predator|website=phys.org|access-date=August 23, 2021|archive-date=August 23, 2021|archive-url=https://web.archive.org/web/20210823232627/https://phys.org/news/2021-08-rex-jaw-sensors-fearsome-predator.html|url-status=live}}</ref> However, a more recent study reviewing the evolution of the trigeminal canals among sauropsids notes that a much denser network of neurovascular canals in the snout and lower jaw is more commonly encountered in aquatic or semiaquatic taxa (e.g., ''[[Spinosaurus]]'', ''[[Halszkaraptor]]'', ''[[Plesiosaurus]]''), and taxa that developed a rhamphotheca (e.g., ''[[Caenagnathasia]]''), while the network of canals in ''Tyrannosaurus'' appears simpler, though still more derived than in most ornithischians, and overall  
terrestrial taxa such as tyrannosaurids and ''Neovenator'' may have had average facial sensitivity for non-edentulous terrestrial theropods, although further research is needed. The neurovascular canals in ''Tyrannosaurus'' may instead have supported soft tissue structures for thermoregulation or social signaling, the latter of which could be confirmed by the fact that the neurovascular network of canals may have changed during ontogeny.<ref>{{Cite journal|last=Benoit|first=Florian Bouabdellah, Emily Lessner, and Julien|date=January 20, 2022|title=The rostral neurovascular system of Tyrannosaurus rex|url=https://palaeo-electronica.org/content/2022/3518-t-rex-trigeminal-canals|journal=Palaeontologia Electronica|language=English|volume=25|issue=1|pages=1–20|doi=10.26879/1178|s2cid=246204236|issn=1094-8074|doi-access=free|archive-date=March 16, 2022|access-date=January 22, 2022|archive-url=https://web.archive.org/web/20220316214524/https://palaeo-electronica.org/content/2022/3518-t-rex-trigeminal-canals|url-status=live}}</ref>

A study by Grant R. Hurlburt, Ryan C. Ridgely and Lawrence Witmer obtained estimates for [[Encephalization Quotient]]s (EQs), based on reptiles and birds, as well as estimates for the ratio of cerebrum to brain mass. The study concluded that ''Tyrannosaurus'' had the relatively largest brain of all adult non-avian dinosaurs with the exception of certain small maniraptoriforms (''[[Bambiraptor]]'', ''[[Troodon]]'' and ''[[Ornithomimus]]''). The study found that ''Tyrannosaurus'''s relative brain size was still within the range of modern reptiles, being at most 2 [[standard deviations]] above the mean of non-avian reptile EQs. The estimates for the ratio of cerebrum mass to brain mass would range from 47.5 to 49.53 percent. According to the study, this is more than the lowest estimates for extant birds (44.6 percent), but still close to the typical ratios of the smallest sexually mature alligators which range from 45.9–47.9 percent.<ref name="Trexpaleobiologychapter6">{{Cite book |title=Tyrannosaurid Paleobiology |last1=Hurlburt |first1=G. S. |last2=Ridgely |first2=R. C. |last3=Witmer |first3=L. M. |date=July 5, 2013 |publisher=Indiana University Press |isbn=978-0-253-00947-0 |pages=134–154 |chapter=Relative size of brain and cerebrum in Tyrannosaurid dinosaurs: an analysis using brain-endocast quantitative relationships in extant alligators |access-date=October 20, 2013 |editor-last=Parrish |editor-first=M. J. |editor-last2=Molnar |editor-first2=R. E. |editor-last3=Currie |editor-first3=P. J. |editor-last4=Koppelhus |editor-first4=E. B. |chapter-url=https://www.researchgate.net/publication/256536375}}</ref> Other studies, such as those by Steve Brusatte, indicate the encephalization quotient of ''Tyrannosaurus'' was similar in range (2.0–2.4) to a [[chimpanzee]] (2.2–2.5), though this may be debatable as reptilian and mammalian encephalization quotients are not equivalent.<ref>{{cite book|last=Brusatten|first=Steve|title=The Rise and Fall of the Dinosaurs|date=2018|publisher=HarperCollins Publishers|location=New York, New York|isbn=978-0-06-249043-8|page=219}}</ref>