Editing Albertosaurus (section)

===Skull and teeth===
[[File:Albertosaurus skull cast.jpg|thumb|left|Skull cast at the [[Geological Museum in Copenhagen]]]]
The massive [[skull]] of ''Albertosaurus'', which was perched on a muscular, short, S-shaped neck, was about {{convert|1|m|ft|abbr=off}} long in the largest adults.<ref name=currie2003a>{{cite journal |last=Currie |first=Philip J. |author-link=Philip J. Currie |year=2003 |title=Allometric growth in tyrannosaurids (Dinosauria: Theropoda) from the Upper Cretaceous of North America and Asia |journal=Canadian Journal of Earth Sciences |volume=40 |issue=4 |pages=651–665 |doi=10.1139/e02-083 |bibcode=2003CaJES..40..651C |url=http://doc.rero.ch/record/14325/files/PAL_E1505.pdf |archive-date=December 23, 2023 |access-date=January 3, 2023 |archive-url=https://web.archive.org/web/20231223034524/https://doc.rero.ch/record/14325/files/PAL_E1505.pdf |url-status=live }}</ref> Wide openings in the skull, called [[fenestra]]e, provided space for [[muscle]] attachment sites and [[sensory organ]]s that reduced its overall weight. Its long jaws contained, both sides combined, 58 or more banana-shaped teeth. Larger tyrannosaurids possessed fewer teeth, but ''[[Gorgosaurus]]'' had 62. Unlike most theropods, ''Albertosaurus'' and other tyrannosaurids were [[heterodont]], with teeth of different forms depending on their position in the mouth. The [[premaxilla]]ry teeth at the tip of the upper jaw, four per side, were much smaller than the rest, more closely packed, and D-shaped in [[cross section (geometry)|cross section]].<ref name=holtz2004/> Like with ''Tyrannosaurus rex'', the maxillary (cheek) teeth of ''Albertosaurus'' were adapted in general form to resist lateral forces exerted by a struggling prey animal. The bite force of ''Albertosaurus'' was less formidable, however, with the maximum force, by the back teeth, reaching 3,413 Newtons.<ref>{{cite journal | last1 = Reichel | first1 = Miriam | year = 2010 | title = The heterodonty of ''Albertosaurus sarcophagus'' and ''Tyrannosaurus rex'': biomechanical implications inferred through 3-D models | journal = Canadian Journal of Earth Sciences | volume = 47 | issue = 9| pages = 1253–1261 | doi = 10.1139/e10-063 | bibcode = 2010CaJES..47.1253R }}</ref> Above the eyes were short bony crests that may have been brightly coloured in life and possibly used, by males in particular, in courtship to attract a mate.<ref name="ageofdinosaursalbertosaurus">"Albertosaurus." In: Dodson, Peter; Britt, Brooks; Carpenter, Kenneth; Forster, Catherine A.; Gillette, David D.; Norell, Mark A.; Olshevsky, George; Parrish, J. Michael; & Weishampel, David B. ''The Age of Dinosaurs''. Lincolnwood, Illinois: Publications International, Ltd., 1993. pp.&nbsp;106–107. {{ISBN|0-7853-0443-6}}.</ref>

[[File:Albertosaurus NT small.jpg|thumb|[[Life restoration]]]]
In 2001, [[William Abler]] observed that ''Albertosaurus'' [[tooth serrations]] resemble a [[Fracture|crack]] in the tooth ending in a round void called an ampulla.<ref name="abler-2001">Abler, W.L. 2001. A kerf-and-drill model of tyrannosaur tooth serrations. p.&nbsp;84–89. In: ''Mesozoic Vertebrate Life''. Ed.s Tanke, D. H., Carpenter, K., Skrepnick, M. W. Indiana University Press.</ref> Tyrannosaurid teeth were used as holdfasts for pulling flesh off a body, so when a tyrannosaur pulled back on a piece of meat, the tension could cause a purely crack-like serration to spread through the tooth.<ref name="abler-2001" /> However, the presence of the ampulla distributed these forces over a larger [[surface area]] and lessened the risk of damage to the tooth under strain.<ref name="abler-2001" /> The presence of incisions ending in voids has parallels in human engineering. Guitar makers use incisions ending in voids to, as Abler describes, "impart alternating regions of flexibility and rigidity" to wood that they work on.<ref name="abler-2001" /> The use of a [[drill]] to create an "ampulla" of sorts and prevent the propagation of cracks through material is also used to protect aircraft surfaces.<ref name="abler-2001" /> Abler demonstrated that a plexiglass bar with incisions called "kerfs" and drilled holes was more than 25% stronger than one with only regularly placed incisions.<ref name="abler-2001" /> Unlike tyrannosaurs, more ancient predators, like [[phytosaur]]s and ''[[Dimetrodon]]'', had no adaptations to prevent the crack-like serrations of their teeth from spreading when subjected to the forces of feeding.<ref name="abler-2001" />