Late Pleistocene of Southeast Asia

Abstract

The extant vertebrate fauna of Southeast Asia is distributed into two provinces, the Indochinese and the Sundaic, their boundary being located on the Thai Peninsula at Kra Isthmus. This distribution is the consequence of late Pleistocene and Holocene climatic changes. The late Pleistocene mammalian fauna is poorly known but is characterized by the immigration of Homo sapiens into that area and by the extinction, in the Indochinese Province, of Stegodon and spotted hyena and possibly also by the local extinction of giant panda and orangutan. A decrease in temperature, combined with an important sea-level fall, induced the emergence of a large land mass, Sundaland, connecting Borneo, Sumatra, and Java to the mainland. Several savanna-adapted mammals extended their distribution area southward moving the paleo-Kra Isthmus farther south to the Malay Peninsula. However, the rain forest never completely disappeared since many forest mammals are recorded in both provinces. In the Sundaic Province, the immigration of modern elephant and orangutan characterizes the onset of the late Pleistocene, indicating a return to large areas of rain forests during the last interglacial. These species were, however, already present in the Indochinese Province during the middle Pleistocene. The orangutan's present-day restricted range is therefore a relict distribution, similar to that of the giant panda.