Canine crown morphology and sexual dimorphism in the Great apes

• Yamada Hiroyuki

  Department of Oral Anatomy, School of Dentistry, Aichi-Gakuin University

• Hamada Yuzuru

  Primate Research Institute, Kyoto University

• Kunimatsu Yutaka

  Faculty of Business Administration, Ryukoku University

• Nakatsukasa Masato

  Laboratory of Physical Anthropology, Graduate School of Science, Kyoto University

• Ishida Hidemi

  Emeritus Professor, Kyoto University

Bibliographic Information

Other Title

• 大型類人猿4種の犬歯形態と性的二型
• オオガタ ルイジンエン 4シュ ノ ケンシ ケイタイ ト セイテキ ニガタ

Abstract

This paper described crown morphology and sexual dimorphism of the canines in four species of the Great apes; Pongo pygmaeus, Gorilla gorilla, Pan trogrodytes, and Pan paniscus. At lingual view, the contours of maxillary canines in the males had an isosceles triangles with long mesial and distal incisal crests, while those of the females had an equilateral ones. On the other hand, the mandibular canines of both sexes showed a quadrilateral form. In the four species, the mesial shoulder situated closer to the cervical line in the maxillary canine than in the mandibular one. The mesial lingual ridge of maxillary canines runs longitudinally from the cusp tip to the center of cervical ridge, while in the mandibular canines a well-developed distal lingual ridge runs from the cusp tip toward the distal lingual direction in the both sexes. Among the four species, Pongo pygmaeus was characterized by wrinkles on crown surface and a smooth transition between crown and root in males. In Gorilla gorilla, the cervical ridge of the maxillary canine less developed in males, and the notch between the mesial marginal ridge and cervical ridge much developed in the mandibular canine. In the two species of Pan, the distal shoulder of the maxillary canine was situated equal to the mesial shoulder, or closer to the cusp tip than the mesial shoulder in both sexes. In addition, in maxillary canine of Pan paniscus a well-developed distal lingual ridge merged with the cervical ridge, making a L-shaped ridge in both sexes. The sexual dimorphism is significant, not only in size but also in shape and structure of the canine in the four species. The females were characterized as follows: 1) smaller in all sizes, 2) the crown relief were less developed, which gave a blunt and roundish appearance, 3) the mesial shoulder of the mandibular canine was relatively higher, 4) the cervical ridge was more developed. Odontmetrically, the whole canine size was the greatest in Gorilla gorilla, followed by Pongo pygmaeus, Pan troglodytes, and Pan paniscus was the smallest. Male canines were significantly larger than female canines in the basal crown size as well as crown height in both jaws, especially the distance from the cusp tip to the mesial shoulder (CMSD). On the other hand, the enamel bulge of cervical portion in females was, absolutely and relatively, significantly stronger. The canines in four species of the Great apes reveals a definite sexual dimorphism in size and shape, which may reflect social structure.

Journal

• Anthropological Science (Japanese Series)

  Anthropological Science (Japanese Series) 123 (2), 93-109, 2015

  The Anthropological Society of Nippon

Keywords

• Great apes
• canine
• crown morphology
• tooth size
• sexual dimorphism

Details

• CRID: 1390282679445560192
• NII Article ID: 130005113975
• NII Book ID: AA11307827
• DOI: 10.1537/asj.150917
• ISSN: 13488813
• ISSN: 13443992
• NDL BIB ID: 027046814
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I027046814
• Web Site: https://www.jstage.jst.go.jp/article/asj/123/2/123_150917/_pdf
• Web Site: https://search.jamas.or.jp/link/ui/2016220209
• Text Lang: ja
• Data Source:
  • JaLC
  • NDL
  • Crossref
  • CiNii Articles
  • KAKEN
• Abstract License Flag: Disallowed