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An enigmatic hypoplastic defect of the maxillary lateral incisor in recent and fossil orangutans from Sumatra (Pongo abelii) and Borneo (Pongo pygmaeus)

Skinner, Mark F., Skinner, Matthew M., Pilbrow, Varsha C., Hannibal, Darcy L. (2017) An enigmatic hypoplastic defect of the maxillary lateral incisor in recent and fossil orangutans from Sumatra (Pongo abelii) and Borneo (Pongo pygmaeus). International Journal of Primatology, 37 (4-5). pp. 548-567. ISSN 0164-0291. E-ISSN 1573-8604. (doi:10.1007/s10764-016-9920-2) (KAR id:57840)

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Developmental dental pathologies provide insight into health of primates during ontogeny, and are particularly useful for elucidating the environment in which extant and extinct primates matured. Our aim is to evaluate whether the prevalence of an unusual dental defect on the mesiolabial enamel of the upper lateral incisor, thought to reflect dental crowding during maturation, is lesser in female orangutans, with their smaller teeth, than in males; and in Sumatran orangutans, from more optimal developmental habitats, than in those from Borneo. Our sample includes 49 Pongo pygmaeus (87 teeth), 21 P. abelii (38 teeth), Late Pleistocene paleo-orangutans from Sumatra and Vietnam (67 teeth), Late Miocene catarrhines Lufengpithecus lufengensis (2 teeth), and Anapithecus hernyaki (7 teeth). Methods include micro-CT scans, radiography, and dental metrics of anterior teeth. We observed fenestration between incisor crypts and marked crowding of unerupted crowns, which could allow tooth-to-tooth contact. Tooth size does not differ significantly in animals with or without the defect, implicating undergrowth of the jaw as the proximate cause of dental crowding and defect presence. Male orangutans from both islands show more defects than do females. The defect is significantly more common in Bornean orangutans (71 %) compared to Sumatran (29 %). Prevalence among fossil forms falls between these extremes, except that all five individual Anapithecus show one or both incisors with the defect. We conclude that maxillary lateral incisor defect is a common developmental pathology of apes that is minimized in optimal habitats and that such evidence can be used to infer habitat quality in extant and fossil apes.

Item Type: Article
DOI/Identification number: 10.1007/s10764-016-9920-2
Uncontrolled keywords: Anapithecus; Dentition; Growth; Infancy; Lufengpithecus; Paleohealth
Subjects: Q Science > QH Natural history > QH301 Biology
Divisions: Divisions > Division of Human and Social Sciences > School of Anthropology and Conservation
Depositing User: Matthew Skinner
Date Deposited: 11 Oct 2016 07:38 UTC
Last Modified: 09 Dec 2022 04:09 UTC
Resource URI: (The current URI for this page, for reference purposes)
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