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Creators/Authors contains: "Simpson, Emily M"

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  1. With most ungulates absent from Africa until the Miocene, the morphologically diverse hyraxes were a major component of the Eocene-Oligocene community at Quarry L-41 (~34 Ma) in the Fayum Depression, Egypt. However, their foraging strategies are poorly understood. This study focuses on four extinct hyraxes: Thyrohyrax meyeri, Thyrohyrax litholagus, and Megalohyrax eocaneus, all expected to be grazers; and Saghatherium bowni, previously described as a browser. Mesowear can place extinct herbivores on a spectrum from grazer to browser based on the abrasiveness oftheir lifetime diets. Crown height, tooth length, and cusp angle were measured for the first lower molars (M1) in these four hyrax species. Specimens were categorized into Wear Classes (WC), which correspond with developmental age. WC ranged from 1, first adult molar fully erupted, to 8, all molars extremely worn with significant dentin exposure. Change in mean crown height and cusp angle across different wear classes was not significantly different. Nonetheless, apparent trends suggest compositional differences in diet. Change in mean crown height for Saghertherium indicates that it incorporated more graze than browse because M1 wear occurred in earlier WCs and increased throughout life. In contrast, less wear for WC 1 through 4 in Thyrohyrax indicates that it incorporated more browse. This agrees with recently collected carbon isotope data, which suggests that Saghatherium’s diet included more graze than Thyrohyrax’s. These data are consistent with the description ofThyrohyrax as an arboreal browser. The change in mean crown height for Megalohyrax also suggests a less abrasive diet, although sample size for Megalohyrax was smaller. The browse-biased diet for Megalohyrax is surprising, as isotope values suggest a more open environment. Browsing in salt-stressed environments, forest canopies or forest edges could explain these combined data. Megalohyrax could have foraged in a wider variety of environments than the other taxa because its larger size enabled a wider range. By reconstructing the diets and niche partitioning among morphologically diverse hyraxes at L-41, we hope to gain insights about the ecosystem represented by L-41 near the Eocene-Oligocene Boundary (EOB). This locality represents a time of ecological dynamism when many mammalian communities were dramatically restructured, though the impact of the EOB on African mammal communities remains poorly understood. 
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