Fig. 4.

Isotopic cross-plots (δ¹⁸O versus δ¹³C) of (i) tooth enamel from mammalian herbivores of the Ituri forest, a modern evergreen rainforest in Zaire (32), (ii) tooth enamel from Amboseli National Park, a modern savannah in Kenya (33), and (iii) tooth enamel from Miocene ungulates and proboscideans from two intervals of the Potwar Plateau, Pakistan. δ¹⁸O values from (32) were converted from the SMOW standard to PDB (34). To facilitate comparison between modern isotopic data and Miocene data, all modern δ¹³C values were adjusted by +2.5‰ because of changes in atmospheric composition of δ¹³C since the late Miocene.