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Comparative functional analysis of skull morphology of tree-gouging primates.

Publication ,  Journal Article
Vinyard, CJ; Wall, CE; Williams, SH; Hylander, WL
Published in: American journal of physical anthropology
February 2003

Many primates habitually feed on tree exudates such as gums and saps. Among these exudate feeders, Cebuella pygmaea, Callithrix spp., Phaner furcifer, and most likely Euoticus elegantulus elicit exudate flow by biting into trees with their anterior dentition. We define this behavior as gouging. Beyond the recent publication by Dumont ([1997] Am J Phys Anthropol 102:187-202), there have been few attempts to address whether any aspect of skull form in gouging primates relates to this specialized feeding behavior. However, many researchers have proposed that tree gouging results in larger bite force, larger internal skull loads, and larger jaw gapes in comparison to other chewing and biting behaviors. If true, then we might expect primate gougers to exhibit skull modifications that provide increased abilities to produce bite forces at the incisors, withstand loads in the skull, and/or generate large gapes for gouging. We develop 13 morphological predictions based on the expectation that gouging involves relatively large jaw forces and/or jaw gapes. We compare skull shapes for P. furcifer to five cheirogaleid taxa, E. elegantulus to six galagid species, and C. jacchus to two tamarin species, so as to assess whether gouging primates exhibit these predicted morphological shapes. Our results show little morphological evidence for increased force-production or load-resistance abilities in the skulls of these gouging primates. Conversely, these gougers tend to have skull shapes that are advantageous for creating large gapes. For example, all three gouging species have significantly lower condylar heights relative to the toothrow at a given mandibular length in comparison with closely related, nongouging taxa. Lowering the height of the condyle relative to the mandibular toothrow should reduce the stretching of the masseters and medial pterygoids during jaw opening, as well as position the mandibular incisors more anteriorly at wide jaw gapes. In other words, the lower incisors will follow a more vertical trajectory during both jaw opening and closing. We predict, based on these findings, that tree-gouging primates do not generate unusually large forces, but that they do use relatively large gapes during gouging. Of course, in vivo data on jaw forces and jaw gapes are required to reliably assess skull functions during gouging.

Duke Scholars

Published In

American journal of physical anthropology

DOI

EISSN

1096-8644

ISSN

0002-9483

Publication Date

February 2003

Volume

120

Issue

2

Start / End Page

153 / 170

Related Subject Headings

  • Trees
  • Species Specificity
  • Skull
  • Jaw
  • Galago
  • Feeding Behavior
  • Cheirogaleidae
  • Callitrichinae
  • Bite Force
  • Biomechanical Phenomena
 

Citation

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ICMJE
MLA
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Vinyard, C. J., Wall, C. E., Williams, S. H., & Hylander, W. L. (2003). Comparative functional analysis of skull morphology of tree-gouging primates. American Journal of Physical Anthropology, 120(2), 153–170. https://doi.org/10.1002/ajpa.10129
Vinyard, Christopher J., Christine E. Wall, Susan H. Williams, and William L. Hylander. “Comparative functional analysis of skull morphology of tree-gouging primates.American Journal of Physical Anthropology 120, no. 2 (February 2003): 153–70. https://doi.org/10.1002/ajpa.10129.
Vinyard CJ, Wall CE, Williams SH, Hylander WL. Comparative functional analysis of skull morphology of tree-gouging primates. American journal of physical anthropology. 2003 Feb;120(2):153–70.
Vinyard, Christopher J., et al. “Comparative functional analysis of skull morphology of tree-gouging primates.American Journal of Physical Anthropology, vol. 120, no. 2, Feb. 2003, pp. 153–70. Epmc, doi:10.1002/ajpa.10129.
Vinyard CJ, Wall CE, Williams SH, Hylander WL. Comparative functional analysis of skull morphology of tree-gouging primates. American journal of physical anthropology. 2003 Feb;120(2):153–170.
Journal cover image

Published In

American journal of physical anthropology

DOI

EISSN

1096-8644

ISSN

0002-9483

Publication Date

February 2003

Volume

120

Issue

2

Start / End Page

153 / 170

Related Subject Headings

  • Trees
  • Species Specificity
  • Skull
  • Jaw
  • Galago
  • Feeding Behavior
  • Cheirogaleidae
  • Callitrichinae
  • Bite Force
  • Biomechanical Phenomena