Quaternary environments and the evolution of primates in East Asia, with notes on two new specimens of fossil cercopithecidae from China

Primate faunas in East Asia since the mid-Tertiary have undergone a series of major changes in response to a complex sequence of environmental changes. As a consequence of the Himalayan orogeny and the rapid, episodic uplift of the Tibetan plateau, the climate of East Asia during the late Tertiary became monsoonal and thus more strongly seasonal. This led to the expansion of seasonal tropical forests and, in some areas, grasslands. During the Pleistocene, the climatic consequences of continued rapid uplift of the Tibetan plateau and other land masses (e.g. the Qinling mountains) were combined with those of glaciations, resulting in dramatic climatic oscillations between warm-humid and cold-dry phases. The contraction of tropical environments that began in the late Tertiary reached its peak at the last glacial maximum (LGM) and was responsible for the decline in the distribution and diversity of hominoids in East Asia. Cercopithecids, which were only minor elements of the late Tertiary primate faunas, colonized tropical, subtropical and temperate environments in the Pleistocene and were able to reradiate into those environments after the LGM. The abilities of monkeys to populate a wide range of terrestrial environments (eurytopy) contrast with those of apes, which are restricted to tropical forest environments (stenotopy).