Note on the Occurrence of the Latest Pleistocene Mammals from Lake Nojiri (Part 1)

Abstract

During the excavation of 1962-1965, numerous mammalian bones were unearthed from the bottom of Lake Nojiri at Tategahana, northern part of Nagano-ken, Central Japan. Fossil bones were embedded in the Latest Pleistocene lacustrine deposits of the middle part of the Nojiriko Formation of which the radiocarbon date is 21, 600±900 yrs.B.P. and 31, 100±2500 yrs.B.P. From the stratigraphical view point, the age of the fossil bones is estimated as twenty thousand years before. In spite of the abundance of fossil bones, only two species of gregorious hervivores, Nauman's Elephant Elephas naumanni MAKIYAMA and Yabe's Giant Deer Shinomegaceroides yabei SHIKAMA, are identified. As the range of E. naumanni in Japan has been considered to be from the Middle to the Late Pleistocene, the present specimens represent the latest survivor. In this paper, the description of E. naumanni of Lake Nojiri is given. In comparison with other specimens including type specimens the authors state that Lake Nojiri specimens are characterized in having eurycronine and hypsodont molars with thin enamel, and that E. naumanni of Lake Nojiri was an inhabitant of cool temperate or subarctic environment. Near the fossil locality the Late Paleolithic site of Sugikubo is located, and at the fossil locality some tips of the stone implements were discovered in association with fossil bones. But the definite relation between the mammalian remains and the Paleolithic site has not yet been confirmed.