ANCIENT DIETS INDICATE SIGNIFICANT UPLIFT OF SOUTHERN TIBET AFTER 7 MYR AGO

The Tibetan Plateau, formed as a result of the India-Asia collision, is the most imposing topographic feature on Earth's surface and may have played a critical role in controlling global climate change. Yet, the history of the uplift of the Tibetan plateau is still a contentious issue. In particular, the elevation of the plateau during Neogene times – a crucial period in the development of the Asian monsoons and C4 ecosystems – remains uncertain. Here we present carbon isotopic evidence, preserved in tooth enamel from 7 million-year-old horses and rhinos from the high Himalayas, indicating that the diets of these ancient mammals were very different from those of modern herbivores in the area and consisted of both C3 and C4 vegetation. The presence of significant amounts of C4 grasses in the diets of these ancient mammals indicates that the climate in the area was much warmer and the elevation was much lower in the late Miocene than it is today, implying that the present elevation of the area must have been attained after 7 Myr ago, much later than generally believed.