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Like other apes, ''Gigantopithecus'' had a [[dental formula]] of {{DentalFormula|upper=2.1.2.3|lower=2.1.2.3}}, with two [[incisor]]s, one canine, two premolars, and three molars in each half of the jaw for both jaws.<ref name=ZhangHarrison2017/> The canines, due to a lack of honing facets (which keep them sharp) and their overall stoutness, have been suggested to have functioned like premolars and molars (cheek teeth). Like other apes with enlarged molars, the incisors of ''Gigantopithecus'' are reduced.<ref name=Dean2003/><ref name=Ciochon1996>{{cite journal |last=Ciochon |first=R. |author-link=Russell Ciochon |year=1996 |title=Dated Co-Occurrence of ''Homo erectus'' and ''Gigantopithecus'' from Tham Khuyen Cave, Vietnam |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=93 |issue=7 |pages=3016–3020 |doi=10.1073/pnas.93.7.3016 |pmid=8610161 |pmc=39753|bibcode=1996PNAS...93.3016C |display-authors=etal|doi-access=free }}</ref> Wearing on the tongue-side of the incisors (the lingual face), which can extend as far down as the [[tooth root]], suggests an [[underbite]].<ref name=ZhangHarrison2017/> Overall mandibular anatomy and tooth wearing suggests a side-to-side movement of the jaw while chewing (lateral excursion).<ref name=Kono2014/> The incisors and canines have extremely long tooth roots, at least double the length of the [[tooth crown]] (the visible part of the tooth). These teeth were closely packed together.<ref name=ZhangHarrison2017/>
In the upper jaw, the average size of the 1st premolar (P<sup>3</sup>), 2nd premolar (P<sup>4</sup>), 1st and 2nd molar (which are difficult to distinguish, M<sup>1/2</sup>), and 3rd molar (M<sup>3</sup>) are:<ref name=ZhangHarrison2017/>
In the upper jaw, the first premolar (P<sup>3</sup>) averages {{convert|20.3|x|15.2|mm|sigfig=1|abbr=in|frac=32}} in surface area, the second premolar (P<sup>4</sup>) {{convert|15.2|x|16.4|mm|abbr=in|frac=32}}, the first and/or second molars (M<sup>1/2</sup>, which are difficult to distinguish) {{convert|19.8|x|17.5|mm|abbr=in|frac=32}}, and the third molar (M<sup>3</sup>) {{convert|20.3|x|17.3|mm|abbr=in|frac=32}}. In the lower jaw, P<sub>3</sub> averages {{convert|15.1|x|20.3|mm|abbr=in|frac=32}}, P<sub>4</sub> {{convert|13.7|x|20.3|mm|abbr=in|frac=32}}, M<sub>1/2</sub> {{convert|18.1|x|20.8|mm|abbr=in|frac=32}}, and M<sub>3</sub> {{convert|16.9|x|19.6|mm|abbr=in|frac=32}}. The molars are the biggest of any known ape.<ref name=ZhangHarrison2017/> Teeth continually evolved to become larger and larger.<ref name=Shao2017/> The premolars are high-crowned, and the lower have two tooth roots, whereas the upper have three. The lower molars are low-crowned, long and narrow, and waist at the midline—which is more pronounced in the lower molars—with low-lying and bulbous cusps and rounded-off crests.<ref name=ZhangHarrison2017/>▼
*P<sup>3</sup> {{convert|20.3|x|15.2|mm|sigfig=1|abbr=in|frac=32}} in surface area
*P<sup>4</sup> {{convert|15.2|x|16.4|mm|abbr=in|frac=32}}
*M<sup>1/2</sup> {{convert|19.8|x|17.5|mm|abbr=in|frac=32}}
*M<sup>3</sup> {{convert|20.3|x|17.3|mm|abbr=in|frac=32}}.
In the lower jaw:<ref name=ZhangHarrison2017/>
*P<sub>3</sub> {{convert|15.1|x|20.3|mm|abbr=in|frac=32}}
*P<sub>4</sub> {{convert|13.7|x|20.3|mm|abbr=in|frac=32}}
*M<sub>1/2</sub> {{convert|18.1|x|20.8|mm|abbr=in|frac=32}},
*M<sub>3</sub> {{convert|16.9|x|19.6|mm|abbr=in|frac=32}}.
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[[File:Giganthopithecus blacki, molar.jpeg|thumb|''Gigantopithecus'' molar]]
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