1Department of Natural Sciences, University of Findlay, 2Department of Biological Anthropology and Anatomy, Duke University
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Alouatta humeral and femoral properties were examined for sex differences. Possible age-related differences were also explored. The first expectation was that males would have greater humeral midshaft cross-sectional properties relative to body mass than females. The second expectation was that older age categories would show decreased cortical thickness compared to younger adult age categories. Both of these expectations were based on human patterns.
The sample consisted of wild Alouatta caraya (N = 20), A. palliata (N= 20), and A. seniculus (N = 21) specimens sorted into age categories based on patterns of dentition and epiphyseal fusion. Most had associated body masses. Properties analyzed include humeral and femoral lengths, midshaft cross-sectional cortical and total areas, and femoral head optical density. Age categories were compared using t-tests. Data were log-transformed prior to least squares regression of variables. Future work includes fitting the data using reduced major axis. ANOVA was used to compare slopes and elevations.
Results indicate that Alouatta males have greater humeral properties, relative to body mass. This supports the expectation that males have more robust forelimbs than females. Results also indicate that females have greater femoral head optical density than males, compared to body mass. Optical density graphs show considerable scatter so this result is viewed with caution. Comparisons of age categories within both male and female samples do not indicate that older monkeys have thinner cortices or lower femoral head mass. Perhaps few feral monkeys reach senescence.