page_title: Tyrannosaurus
section_title: Skeleton
hierarchical_section_title: Tyrannosaurus / Description / Skeleton
caption_attribution_description: English: A life restoration of the theropod dinosaur Tyrannosaurus rex. • The proportions are based on a Tyrannosaurus skeletal reconstruction by Scott Hartman [1] • It's not clear whether derived tyrannosaurs would have been covered in scales, feathers, or a combanation of both. A few small skin impressions have been described for Tyrannosaurus which show small pebbled skin; close relatives, Tarbosaurus and Gorgosaurus are known to have similar pebbled skin.&#91;1&#93; &#91;2&#93; Skin impressions from the closley related Gorgosaurus are reported to show both smooth, naked skin and scales.&#91;3&#93; &#91;4&#93; A 2017 study looked at a variety of tyranosaurid skin impressions and came to the conclusion that derived tyrannosaurs were probably scaly over most their body. &#91;2&#93; What complicates the issue is that most coelurosaur fossils show feathers covering thier bodies and inference would suggest the same for tyrannosaurs. The smaller basal tyrannosauriod Dilong and the larger tyrannosauroid Yutyrannus also preserve feather impressions. This raises the probability that, derived tyrannosaurs had a mix of feathers and scales on different parts of the body or that feathers were lost as individuals reach maturity &#91;5&#93; &#91;6&#93; A study published in 2017 looked at the texture of a tyrannosaurs skull bones and suggested that there may have been large, flat Crocodile-like skin cracks/scales on the front of the snout of tyrannosaurids. &#91;7&#93; The details on the head in this restoration are based on an similar interpetration of bone texture by Mark Witton in which he suggests that certain areas of the head were covered in a cornified sheath as well as scales. [2] I often update my images. If you want to post any of my images on a website, if possible, don’t host/save it to the website server. I’d prefer it if the image's Wikimedia URL is used or a link is provided to this page. This allows updates to be seen by future viewers. Thanks. References ↑ Currie, Philip; Badamgarav, Demchig; Koppelhus, Eva.&#32;(2003).&#32;"'The First Late Cretaceous Footprints from the Nemegt Locality in the Gobi of Mongolia'"&#32;(PDF). Ichnos&#32;10&#32;(1): 1-13. ↑ a b Bell, P R., et al&#32;(2017).&#32;"Tyrannosauroid integument reveals conflicting patterns of gigantism and feather evolution". Biology Letters. DOI:10.1098/rsbl.2017.0092. ↑ Currie, P. (2001). 2001 A. Watson Armour Symposium: The Paleobiology and Phylogenetics of Large Theropods. Field Museum of Natural History, Chicago. ↑ Carpenter, Kenneth (1997) "Tyrannosauridae" in Currie, Philip J. &amp; Padian, Kevin (eds.). , ed. Encyclopedia of Dinosaurs, San Diego&#58; &#32;Academic Press, pp.&#160;768 ISBN&#58; 0-12-226810-5.&#32; ↑ Xu, X., Norell, M. A., Kuang, X., Wang, X., Zhao, Q., Jia, C.&#32;(2004).&#32;"Basal tyrannosauroids from China and evidence for protofeathers in tyrannosauroids". Nature&#32;431: 680–684. DOI:10.1038/nature02855. ↑ &#32;(2012).&#32;"A gigantic feathered dinosaur from the Lower Cretaceous of China"&#32;(PDF). Nature&#32;484: 92–95. DOI:10.1038/nature10906. PMID 22481363. ↑ &#32;(2017).&#32;"A new tyrannosaur with evidence for anagenesis and crocodile-like facial sensory system". Scientific Reports&#32;7: 44942. DOI:10.1038/srep44942.
context_page_description: Tyrannosaurus is a genus of coelurosaurian theropod dinosaurs. The species Tyrannosaurus rex, often called T. rex or colloquially T-Rex, is one of the most well-represented of the large theropods. Tyrannosaurus lived throughout what is now western North America, on what was then an island continent known as Laramidia. Tyrannosaurus had a much wider range than other tyrannosaurids. Fossils are found in a variety of rock formations dating to the Maastrichtian age of the upper Cretaceous period, 68 to 66 million years ago. It was the last known member of the tyrannosaurids, and among the last non-avian dinosaurs to exist before the Cretaceous–Paleogene extinction event.
  Like other tyrannosaurids, Tyrannosaurus was a bipedal carnivore with a massive skull balanced by a long, heavy tail. Relative to its large and powerful hind limbs, Tyrannosaurus forelimbs were short but unusually powerful for their size and had two clawed digits. The most complete specimen measures up to 12.3 meters in length though T. rex could grow to lengths of over 12.3 m, up to 3.66 m tall at the hips, and according to most modern estimates 8.4 metric tons to 14 metric tons in weight.
context_section_description: The largest known T. rex skull is 1.52 meters (5 ft) in length. Large fenestrae (openings) in the skull reduced weight, as in all carnivorous theropods. In other respects Tyrannosaurus'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. The skull bones were massive and the nasals and some other bones were fused, preventing movement between them; but many were 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. 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.
  The teeth of T. rex displayed marked heterodonty (differences in shape). The premaxillary 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 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. Those in the upper jaw, twelve per side in mature individuals, were larger than their counterparts of the lower jaw, except at the rear. The largest found so far is estimated to have been 30.5 centimeters (12 in) long including the root when the animal was alive, making it the largest tooth of any carnivorous dinosaur yet found. The lower jaw was robust. Its front dentary bone bore thirteen teeth. Behind the tooth row, the lower jaw became notably taller. The upper and lower jaws of Tyrannosaurus, like those of many dinosaurs, possessed numerous foramina, or small holes in the bone. Various functions have been proposed for these foramina, such as a crocodile-like sensory system or evidence of extra-oral structures such as scales or potentially lips.
  The vertebral column of Tyrannosaurus consisted of ten neck vertebrae, thirteen back vertebrae and five sacral vertebrae. The number of tail vertebrae is unknown and could well have varied between individuals but probably numbered at least forty. Sue was mounted with forty-seven of such caudal vertebrae. The neck of T. rex formed a natural S-shaped curve like that of other theropods. Compared to these, it was exceptionally short, deep and muscular to support the massive head. The second vertebra, the axis, was especially short. The remaining neck vertebrae were weakly opisthocoelous, i.e. with a convex front of the vertebral body and a concave rear. The vertebral bodies had single pleurocoels, pneumatic depressions created by air sacs, on their sides. The vertebral bodies of the torso were robust but with a narrow waist. Their undersides were keeled. The front sides were concave with a deep vertical trough. They had large pleurocoels. Their neural spines had very rough front and rear sides for the attachment of strong tendons. The sacral vertebrae were fused to each other, both in their vertebral bodies and neural spines. They were pneumatized. They were connected to the pelvis by transverse processes and sacral ribs. The tail was heavy and moderately long, in order to balance the massive head and torso and to provide space for massive locomotor muscles that attached to the thighbones. The thirteenth tail vertebra formed the transition point between the deep tail base and the middle tail that was stiffened by rather long front articulation processes. The underside of the trunk was covered by eighteen or nineteen pairs of segmented belly ribs.
  
  The shoulder girdle was longer than the entire forelimb. The shoulder blade had a narrow
caption: Restoration showing scaly skin with sparse feathering, and lipped jaws
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