New materials of Stegodon orientalis OWEN from Kuzuu-machi, Tochigi Prefecture

Abstract

Recently new materials of Stegodon orientalis OWEN were discovered from Murakashi Quarry, Kuzuu-machi, Aso district, Tochigi Prefecture. Those materials consist of fossil bones and molars obtained from the fissure-filling deposits, and are considered to belong to one young individual. The molars are composed of ₂DP, DP₄, M₁. The measurements of those molars indicate that, for example in the case of M₁, there are some characteristics of narrow crown breadth, high lamellar frequency and thin enamel. It is remarkable that these characteristics are common to other two specimens from Kuzuu area which were formerly described by TOKUNAGA and TAKAI (1938) and SHIKAMA (1949). Nevertheless, in comparison with other specimens of Japan and China, there seems to be some differences with each other in some degrees. It may suggest that the differences are due to geographical or chronological variation. According to the analysis of pumice grains included in the yielded sediments, the horizon of the present materials is correlative with the Lower Kuzuu formation and is contemporaneous with the Tama Loam stage of the Middle Pleistocene.