Abstract: We use carbon isotopes in fossil tooth enamel to infer dietary preferences in Baodean (Late Miocene) gazelles from three classical localities in North China, along with putative browsers (Cervidae) and grazers (Hipparion) from the same localities. The results suggest that these Late Miocene ecosystems were dominated by C3 vegetation, but contained a small fraction of C4 vegetation (probably less than ~30%). We find that the higher-crowned gazelles (Gazella dorcadoides-type) consumed up to ~20% C4 plants, whereas G. paotehensis-type gazelles (intermediate crown-height forms) and G. gaudryi-type gazelles (low-crowned forms) had essentially pure C3 diets. Cervidae consumed pure C3 vegetation, while Hipparion consumed some C4 vegetation and is statistically indistinguishable from G. dorcadoides-type gazelles. The carbon isotope data are consistent with a primarily browsing diet in G. gaudryi-type gazelles, and a larger fraction of graze in the diet of G. dorcadoides-type gazelles. Taken with the distributions of these taxa, the data support the established concept of relatively closed habitats in the southeast CLP (Chinese Loess Plateau) compared to the northwest CLP during the Late Miocene. The direction and pattern of this environmental gradient may be an early signature of the East Asian Monsoon system in this region.