Late Miocene Climate Cooling Contributed to the Disappearance of Hominoids in Yunnan Region, Southwestern China.

The relationship between long‐sequence climate change and Miocene hominoid evolution in the Yunnan region of southwestern China has recently received some attention, partly because this region has been regarded as a "refugium" for hominoids at the end of the Miocene. Here, we carry out a high‐resolution reconstruction of climate evolution in the Zhaotong Basin of Yunnan through the late Miocene to Pliocene using chemical weathering indices and other proxies. The results reveal gradual cooling within generally warm and humid conditions from 8.8–6.2 Ma; three more marked cooling episodes from 6.2–5.0 Ma; cool and humid conditions from 5.0–2.8 Ma; finally, cold and humid conditions from 2.8–2.62 Ma. The evidence is compatible with a scenario in which terminal Miocene cooling episodes within a prevailing warm and humid climate, and associated changes in vegetation, may have been critical factors in the disappearance of hominoids from this region. Plain Language Summary: Orangutans are the only Asian great apes living today, the sole remnants of a far more important radiation that occurred during the Miocene, when several species of apes are recorded from Asia, from Turkey into Pakistan, and India, and China. The Yunnan region of southwestern China has long been regarded as a "refugium" for late Miocene hominoids, as most species became extinct in Africa, Europe, and South Asia. But what caused Miocene hominoids to disappear in the Yunnan region at the southeastern margin of the Tibetan Plateau? We reconstructed a high‐resolution climate records from sediment chemical weathering, and our results suggest that warm and humid climate conditions prevailed during the known period of hominoid occupation in the region, but episodes of climate cooling at 6.2 Ma may have disrupted "refugium" and resulted in the disappearance of hominoids from the region. Key Points: Generally warm and humid climate conditions during the late Miocene in southwest China provide a "refugium" for hominoids in this regionThere were four stages of climate change during the late Miocene through Pliocene in the region, including four episodes of cooler climateThe terminal Miocene cooling episodes may have been factors in the disappearance of hominoids from this region [ABSTRACT FROM AUTHOR]