CLASSIFICATION AND EVOLUTION OF ASIAN COLOBINES

In order to study the differentiation of Asian colobines, 14 variables measured on 123 skulls, including Rhinopithecus, Presbytis, Presbytis cus (Rhinopithecus avunculus), Pygathrix and Nasalis were analyzed by one-way, cluster and discriminant function analyses. Information on pa leoenvironmental changes in China and southeast Asia since the late Te rtiary was used to examine the influences of migratory routes and rang e of distribution in Asian colobines. A cladogram for 6 genera of Asia n colobines was constructed from the results of various analyses. Some new points or revisions were suggested: (1) Following one of two migr atory routes, ancient species of Asian colobines perhaps passed throug h Xizang (Tibet) along the northern bank of the Tethys sea and through the Heng Duan Shan regions of Yunnan into Vietnam. An ancient landmas s linking Yunnan and Xizang was already present on the east bank of th e Tethys sea. Accordingly, Asian colobines would have two centers of e volutionary origin: Sundaland and the Heng Duan Shan regions of China. (2) Pygathrix shares more cranial features with Presbytiscus than wit h Rhinopithecus. This differs somewhat from the conclusion reached by Groves. (3) Nasalis (karyotype: 2n = 48) may be the most primitive gen us among Asian colobines. Certain features shared with Rhinopithecus, e.g. large body size, terrestrial activity and limb proportions, can b e interpreted as symple-siomorphic characters. (4) Rhinopithecus, with respect to craniofacial features, is a special case among Asian colob ines. It combines a high degree of evolutionary specialization with re tention of some primitive features thought to have been present in the ancestral Asian colobine.