Fossil Pongo from the Early Pleistocene Gigantopithecus fauna of Chongzuo, Guangxi, southern China

Abstract

More than seventy isolated teeth of fossil Pongo are reported from Baikong, Juyuan and Queque Caves in Chongzuo, Guangxi, southern China. This Early Pleistocene material dates from 2.0 to 1.0 Ma based on faunal correlations and paleomagnetic analyses. The teeth from Chongzuo are generally morphologically very similar to those of extant species of Pongo, but are much larger in size. All of the fossil specimens can be attributed to Pongo weidenreichi, which is a typical member of the Early and Middle Pleistocene fauna of southern China and Vietnam. The identification of more detailed species-specific characteristics of P. weidenreichi will require larger samples. In addition, many of the systematic problems associated with fossil Pongo remain unresolved, but a provisional taxonomic scheme is presented that better reflects our current understanding of species-level diversity. Five extinct species of Pongo are recognized: P. weidenreichi from the Early and Middle Pleistocene of China and the Middle Pleistocene of Vietnam, Pongo palaeosumatrensis from the Late Pleistocene of Sumatra, Pongo javensis from the Late Pleistocene of Java, Pongo duboisi from the Late Pleistocene of Sumatra, and Pongo devosi from the Late Pleistocene of China and Vietnam. P. weidenreichi, which is the earliest-known species of orang-utan, is replaced during the Late Pleistocene by a smaller species, P. devosi. Pongo becomes extinct in China during the Late Pleistocene, but may have survived in Vietnam and Cambodia into the Holocene. In island Southeast Asia, orang-utans were present on Java by at least the Middle Pleistocene and they continued into the Late Pleistocene as P. javensis. The Javan lineage of Pongo is more diminutive, at least dentally, than broadly contemporary species on mainland Asia, Sumatra and Borneo. Two species of Pongo are recognized from Late Pleistocene localities in the Padang Highlands of Sumatra. A relatively large species, P. duboisi, is known from Lida Ayer and Djambu, while a somewhat smaller species, P. palaeosumatrensis, is known from slightly younger deposits from Sibrambang. The latter two taxa possibly represent time-successive members of the Pongo abelii lineage or are members of an older lineage of Pongo, broadly distributed across Sundaland, that was the sister taxon of Pongo pygmaeus and P. abelii. As noted by previous researchers, the fossil record provides evidence of a trend in Pongo to reduce the size of its dentition during the Pleistocene, but this overall trend was apparently influenced by various extrinsic factors that resulted in spatio-temporal heterogeneity in dental size.