樺太野頃附近海岸産マンモス象化石
1938 年 50 巻 10 号 p. 460-460_1,12
詳細
1938 年 50 巻 10 号 p. 460-460_1,12
Lately the writer obtained a mammoth tooth found on a seabeach between Nokoro and Tirie in South Sakhalin.
The degree of fossilization of the present specimen is fairly high, chocolate brown in colour with a strong lustre. In the crown view, the outerside is an acute triangle, and the side view is nearly a rectangle. It consists of seventeen ridges, excluding several ones which are inferred to have been lost on the occasion of digging. Of these the anterior ridges are almost straight in the sideview, while the posterior ones are more or less curved, some of them being S-shaped. The grinding surface is flat. The enamel layers are flexuous, but nearly straight; in this respect they differ from those of Manchurian Mammoth. This specimen is perhaps the third molar on the left mandible.
Length of crown 205mm. Ridges 17
Max. width of crown 80mm. Interspaces of ridges 5mm
Length of grinding surface 115mm. Thickness of ridges 5mm±
Height 120mm. Thickness of enamel layers 1.2mm±
Height of crown 80mm . Frequency 10±
The present molar is determined from these measurements to belong to Elephas primigenius (Blum). In many respects the sample has a close resemblance to that described by Mr. Sasa and thus it is considered to have been derived probably from the Rukutama Series of Upper Diluvial age.
The present specimen will add one valuable material to the problem upon the palaeogeographical connection between Sakhalin and the Asiatic Continent in this age.
