Fig. 2.

Carbon isotope record from pedogenic carbonates (12, 14) and mammalian tooth enamel (15–17, this study) show a pronounced shift to lighter values starting ≈8.5 Ma. Over the well sampled interval from 9.5 to 7.0 Ma, mammalian δ¹³C values vary more than do paleosol values, indicating that mammalian herbivores sampled a broader range of habitats than documented by the paleosol record. To facilitate comparison of paleosol and mammal δ¹³C values with respect to vegetation, all paleosol values were adjusted by −1‰ because the fractionation values (vegetation to palesol carbonate, vegetation to mammalian enamel) differ by this amount.