Abstract: Since 1975 over 1, 000 teeth (isolated and attached to the jaws) of Ramapithecus and Sivapithecus have been collected at the Shihuiba site in Lufeng County, Yunnan Province. The morphological deseription and comparison of the materials show that many characters of Ramapithecus are consistent with those of Sivapithecus, but their canines and lower premolars exhibit bigger differences possibly of different sex. On the basis of the comparison with the living apes, they are similar to those of orang-utan in many features, but very different from gorilla and chimpanzee. One possibility is that Lufeng Ramapithecus and Sivapithecus are of the different sex of the same form, and related closely to the orang-utan.
However, on the other hand, the teeth of Lufeng Ramapithecus have some characters approach to those of Australopithecus afarensis and A. africanus, while the big canines of Sivapithecus are very different from those of australopithecines. Thus another possibility is that Lufeng Ramapithecus and Sivapithecus are two different forms: the former may be a member of the early hominid evolving to australopithecines, and the latter seems to be more similar to orang-utan.

Key words: Lufeng; Ramapithecus; Sivapithecus