The 82nd Annual Meeting of the American Association of Physical Anthropologists (2013)

The dietary competitive environment of early Eocene euprimates in North America


Institute of Human Origins, School of Human Evolution and Social Change, Arizona State University

Saturday 4:00-4:15, Ballroom A Add to calendar

The earliest Eocene marked the appearance of the first North American euprimates. Despite the fact that leading hypotheses assert that traits involved in food acquisition underlie euprimate origination and early diversification, the precise role that dietary competition played in establishing euprimates as successful members of mammalian communities is unclear. This is because the degree of niche overlap between euprimates and all likely mammalian dietary competitors (“euprimate guild”) is unknown. This research determines the temporal pattern of niche overlap within an Eocene euprimate guild and elucidates the nature of dietary competitive interactions surrounding the earliest euprimates in North America.

To evaluate the validity of using dental morphology to reconstruct dietary niche overlap, a discriminant function analysis was performed on nineteen 3D molar measurements in two extant euprimate guilds (Balta, Peru; Mindanao, Philippines; 106 species). Results showed that dietary niche reclassification rates were high (87%). Thus, a PCA of these molar measurements from an Eocene euprimate guild (Bighorn Basin, Wyoming) was conducted, and multidimensional polygons, each representing a species’ dietary niche, were derived from this analysis. Calculation of an F-statistic using Euclidean distances associated with these polygons revealed that dietary niches of Eocene euprimates overlapped with some, but not all, contemporaneous non-euprimate species (p<0.05). Furthermore, correlation analyses of polygon distributions demonstrated that patterns of competition changed over the duration of the Wasatchian. This suggests that the dietary competitive environment of the earliest North American euprimates was complex, and thus that diet had a variable effect on the course of this euprimate radiation.

This research was supported by Sigma Xi, the National Science Foundation (NSF-BCS 1155997), and the Graduate Student and Professional Association and School of Human Evolution and Social Change at Arizona State University. NSF support was also provided to K.D. Rose, from whom fossil specimens were obtained.

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