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Craniodental Allometry, Prenatal Growth Rates, and the Evolutionary Loss of the Third Molars in New World Monkeys


Monson, Tesla A; Coleman, Jeffrey L; Hlusko, Leslea J (2019). Craniodental Allometry, Prenatal Growth Rates, and the Evolutionary Loss of the Third Molars in New World Monkeys. Anatomical Record, 302(8):1419-1433.

Abstract

A growing body of literature demonstrates that genetic patterning mechanisms underlie the relative proportions of the mammalian postcanine dentition with the third molar being key to understanding variation within the molar row. With this relatively recent insight, there has been renewed interest in mammalian taxa that have lost the third molars. Within platyrrhines, the marmosets and tamarins (Callitrichidae family) are characterized by small body size, claw‐like nails, twinning, and reduced molar number. Small body size is hypothesized to have resulted in the third molar being crowded out of the jaws leading to its evolutionary loss in this family. To further explore this hypothesis, we measured the cranium and dentition of 142 individuals spanning all five platyrrhine families. These data reveal that callitrichids have a significantly smaller proportion of mandibular postcanine tooth row length relative to other platyrrhines, refuting the “crowding out” hypothesis. However, postcanine tooth row length is significantly correlated with mandibular length and cranial length (P < 0.01) across all platyrrhines providing evidence for a strong allometric association between postcanine tooth row length and body size more generally. The small body size that characterizes callitrichids results in part from slower prenatal growth rates. Given the allometric relationship between postcanine tooth row length and body size, reported here and in previous studies, we hypothesize that the evolutionary loss of the third molars in callitrichids results from the inhibition of third molar development as a consequence of the slower prenatal growth rates associated with small body size in this family. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc.

Abstract

A growing body of literature demonstrates that genetic patterning mechanisms underlie the relative proportions of the mammalian postcanine dentition with the third molar being key to understanding variation within the molar row. With this relatively recent insight, there has been renewed interest in mammalian taxa that have lost the third molars. Within platyrrhines, the marmosets and tamarins (Callitrichidae family) are characterized by small body size, claw‐like nails, twinning, and reduced molar number. Small body size is hypothesized to have resulted in the third molar being crowded out of the jaws leading to its evolutionary loss in this family. To further explore this hypothesis, we measured the cranium and dentition of 142 individuals spanning all five platyrrhine families. These data reveal that callitrichids have a significantly smaller proportion of mandibular postcanine tooth row length relative to other platyrrhines, refuting the “crowding out” hypothesis. However, postcanine tooth row length is significantly correlated with mandibular length and cranial length (P < 0.01) across all platyrrhines providing evidence for a strong allometric association between postcanine tooth row length and body size more generally. The small body size that characterizes callitrichids results in part from slower prenatal growth rates. Given the allometric relationship between postcanine tooth row length and body size, reported here and in previous studies, we hypothesize that the evolutionary loss of the third molars in callitrichids results from the inhibition of third molar development as a consequence of the slower prenatal growth rates associated with small body size in this family. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Anthropology
Dewey Decimal Classification:300 Social sciences, sociology & anthropology
Uncontrolled Keywords:Biotechnology, Anatomy, Ecology, Evolution, Behavior and Systematics, Histology
Language:English
Date:August 2019
Deposited On:01 Mar 2019 11:56
Last Modified:05 Mar 2020 16:29
Publisher:Wiley-Blackwell Publishing, Inc.
ISSN:1932-8486
OA Status:Closed
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1002/ar.23979
PubMed ID:30315641

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