MANDIBULAR MORPHOLOGY AND DIET IN THE GENUS CEBUS

The influence of hard-object feeding on the size and shape of the mandibular corpus was investigated through a comparative biomechanical analysis of the jaws of adult female Cebus apella and Cebus capucinus. Computed tomography (CT) was used to discern the amount and distribution of cortical bone at M2 and symphyseal cross sections. From these data, the biomechanical properties of the mandibular corpus were determined to assess the structural rigidity of the jaw with respect to the bending, torsional, and shear stresses that occur during mastication and incision. The mandibles of C. apella are demonstrably more robust than those of C. capucinus in terms of biomechanical rigidity; differences in corporeal size rather than shape largely account for the enhanced robusticity in the sample of C. apella. The differences that separate the two taxa probably represent a structural response to the mechanical demands of durophagy in C. apella. These observations suggest that specialization on a diet of hard objects may be expected to result in an overall hypertrophy of bony contours throughout the mandibular corpus.