Cranial Morphometric Analysis on Pygathrix nemaeus and Pygrathrix cinerea

Presenter(s): Carly Pate − Anthropology

Faculty Mentor(s): Larry Ulibarri, Frances White, Stephen Frost

Poster 137

Research Area: Anthropology

This study analyzes cranial morphometric distinction between Pygathrix species. Endangered Pygathrix nemaeus and Critically Endangered Pygathrix cinerea are endemic to Southeast Asia. They are threatened with extinction due to hunting and habitat fragmentation. While generally understudied, osteological analysis on these species are also uncommon due to lack of specimen collections or accessibility. Although their ranges partially overlap, it is possible to distinguish species based on genotypic and phenotypic pelage differences. However, distinctions of skeletal morphology have not been quantified. Pygathrix phylogeny has been debated, with a recent cranial morphometric analysis showing no distinction between species detected through linear measures. Using 3D photogrammetric methods and linear measures, cranial data was collected on an osteological collection of confiscated and captive red-shanked doucs, P. nemaeus, (n=43) and grey-shanked doucs, P. cinerea, (n=23), from the Endangered Primate Rescue Center, Cuc Phuong National Park, Vietnam. Five linear cranial measures indicate no sexual dimorphism between P. cinerea males and females, (n=24, n=19) or between P. nemaeus males and females, (n=17, n=6). One linear measure, anterior foramen magnum to the superior most point on sagittal suture, allowed distinction between species among males, (F 4.37, P<0.05) and among females, (F 10.06, P <0.05). These results indicate a cranial morphometric variation among species. Further 3D shape analysis will continue to explore this distinguishability. Intra- and interspecies variation analyzed morphometrically by 3D photogrammetry can aid in understanding the impacts of species- specific factors such as social structure and feeding ecology on cranial morphological variation.

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