Early Neogene environments in East Africa: Evidence from dental microwear of tragulids

Environmental reconstructions of early Miocene sites are important for understanding the remarkable diversity and abundance of African mammals today. These provide essential context for the faunal interchange that occurred with the appearance of land bridges between Afro-Arabia and Eurasia. Tragulids, for example, were ecological precursors of some bovids, and an appreciation of their habitats during the early Miocene can provide insights into both their adaptive radiation and the environmental backdrop of the larger faunal turnover that followed. Here we reconstruct the diets of four tragulid species from early Miocene of Kenya, Dorcatherium parvum (n=11), D. pigotti (n=7), and D. chappuisi (n=4) from Rusinga Island, and D. songhorensis (n=13) from Songhor, using dental microwear texture analysis. Results indicate that all were likely mixed feeders, though there is variation in the sample. The Songhor species and D. chappuisi are inferred to have been variable grazers, D. pigotti is closer to browsers/generalists in microwear textures, and D. parvum is intermediate. This implies that, despite reconstructions of forested settings, especially at Songhor, at least some grass was available at both sites. It also suggests that the adaptive radiation of tragulids was more diverse in Africa in the past, and that we cannot assume an ancestral diet dominated by fruit and other browse items, as seen in chevrotains today. ► We examine dental microwear of tragulids from early Miocene sites in East Africa. ► Tragulid microwear is used as a proxy for paleoenvironmental reconstruction. ► Dorcatherium at both Rusinga and Songhor appear to have been mixed feeders. ► Dorcatherium probably ate more grass at Songhor and more browse items at Rusinga. ► This suggests availability of graze and browse, and mixed habitats at both sites.