Editing Walrus (section)

===Tusks and dentition===
[[File:WalrusBreathing.jpg|thumb|right|Walrus using its tusks to hang on a breathing hole in the ice near [[St. Lawrence Island]], Bering Sea|alt=Photo of walrus in ice-covered sea.]]
[[File:BLW Teeth in the skull of a large Walrus.jpg|thumb|right|Tooth]]
While this was not true of all extinct walruses,<ref name="US National Library of Medicine">{{cite journal | vauthors = Magallanes I, Parham JF, Santos GP, Velez-Juarbe J | title = A new tuskless walrus from the Miocene of Orange County, California, with comments on the diversity and taxonomy of odobenids | journal = PeerJ | volume = 6 | pages = e5708 | date = 2018 | pmid = 30345169 | pmc = 6188011 | doi = 10.7717/peerj.5708 | doi-access = free }}</ref> the most prominent feature of the living species is its long tusks. These are elongated [[canine teeth|canines]], which are present in both male and female walruses and can reach a length of 1 m (3&nbsp;ft 3 in) and weigh up to 5.4&nbsp;kg (12&nbsp;lb).<ref>{{cite book| vauthors = Berta A, Sumich JL |year = 1999|title = Marine mammals: evolutionary biology|publisher = Academic Press|location = San Diego, CA|url={{google books |plainurl=y |id=zcycBAAAQBAJ}}}}</ref> Tusks are slightly longer and thicker among males, which use them for fighting, dominance and display; the strongest males with the largest tusks typically dominate social groups. Tusks are also used to form and maintain holes in the ice and aid the walrus in climbing out of water onto ice.<ref name="Fay82">{{cite journal| vauthors = Fay FH |year = 1982|title = Ecology and Biology of the Pacific Walrus, ''Odobenus rosmarus divergens'' Illiger|journal= North American Fauna |volume=74 |pages=1–279 |doi=10.3996/nafa.74.0001|doi-access= free}}</ref> Tusks were once thought to be used to dig out prey from the seabed, but analyses of abrasion patterns on the tusks indicate they are dragged through the sediment while the upper edge of the snout is used for digging.<ref name="Ray06">{{cite journal| vauthors = Ray C, McCormick-Ray J, Berg P, Epstein HE |year = 2006|title = Pacific Walrus: Benthic bioturbator of Beringia|journal = Journal of Experimental Marine Biology and Ecology|pages = 403–419|doi = 10.1016/j.jembe.2005.12.043|volume = 330| issue=1 | bibcode=2006JEMBE.330..403R }}</ref> While the [[dentition]] of walruses is highly variable, they generally have relatively few teeth other than the tusks. The maximal number of teeth is 38 with dentition formula: {{DentalFormula|upper=3.1.4.2|lower=3.1.3.2}}, but over half of the teeth are rudimentary and occur with less than 50% frequency, such that a typical dentition includes only 18 teeth {{DentalFormula|upper=1.1.3.0|lower=0.1.3.0}}<ref name="Fay85"/>