A molar microwear texture analysis of pitheciid primates

Dental microwear textures have been examined for a broad range of extant primates to assess their efficacy for reconstructing diets of fossil species. To date though, no dental microwear texture data have been published for pitheciid molars, despite reported variation in degree of sclerocarpy and, by extension, the fracture properties of foods these platyrrhines eat. While all pitheciids eat hard or tough seeds, Chiropotes and Pithecia have been documented to consume more than Callicebus. In this study, we explored whether measures of molar microwear texture complexity discriminate taxa following variation in reliance upon seeds, and whether dispersion among variables is greatest in Callicebus, which has the most variable diet. Here we report results for a study of microwear textures on M2 “Phase II” facets of Ch. satanas (N = 14), P. irrorata (N = 8), and Ca. moloch (N = 24) from the Brazilian Amazon (Oriximina, UHE Samuel, and Taperinha, respectively). Textures examined using a scanning confocal profiler showed significant differences in central tendencies for three measures: mean dale area (Sda), anisotropy (Str), and heterogeneity (HAsfc9). Ten measures showed significant differences in dispersion, with Callicebus being significantly more variable in eight of those ten. These results demonstrate that the pitheciids with different morphological adaptations and dietary reliance on seeds differ in their dental microwear textures, though less than initially hypothesized. Measures of dispersion, especially, show potential for identifying dietary variability. Two pitheciines (Pithecia and Chiropotes) that rely on seed eating were compared to a pitheciid generalist (Callicebus) for differences in dental microwear using a 150x objective on a scanning confocal profiler. Three measures showed differences in central tendency among taxa, and ten measures showed significant differences in dispersion, with the dietary generalist (Callicebus moloch) being significantly more variable for the majority of measures. This study concludes that dental microwear texture analysis successfully discriminates pitheciine diets from that of Callicebus in terms of dispersion, which may be useful for future studies involving dietary variability.