第四紀の東アジアにおけるバク類の分布

At present, tapirs inhabit dense forests in limited areas of Southeast Asia and Central to South America, but are completely absent from East Asia. In contrast, their fossils abundantly occur in Quaternary deposits of East Asia. This paper presents distribution maps of Quaternary fossils of the tapirs in East Asia with the data sources on which the maps are based. The fossils are assigned to two genera of the family Tapiridae, Tapirus and Megatapirus. The maps indicate that the tapirs were distributed almost exclusively in South China in the Early, Middle, and Late Pleistocene. Purported survival of the tapirs during the Holocene is problematic in South China. On the other hand, fossils of tapirs have not been recorded from the Quaternary of Japan. In the Middle and Upper Pleistocene of South China, fossils of the tapirs are mostly associated with those of the extinct proboscidean species, Stegodon orientalis. This species also occurs in the middle Middle Pleistocene of Japan. These facts indicate that S. orientalis immigrated from South China to Japan in the middle Middle Pleistocene, but the tapirs did not immigrate in association with S. orientalis. It is inferred that stenotopic habits of the tapirs had interfered with their immigration.