房総半島の中部更新統万田野層から産出したステラーカイギュウ (Sirenia : Hydrodamalis gigas)

概要

論文の詳細を見る
An isolated rib bone belonging to the Steller's sea-cow, Hydrodamalis gigas (Zimmermann, 1780), is described from the Middle Pleistocene Mandano Formation of the Boso Peninsula, central Japan. The specimen has a typical sirenian dense bone, and is designated as H. gigas on the basis of its morphological characters, size, geological age, and cool-condition of environment which is suggested by molluscan assemblage. The shape of cross section and curvature of the specimen indicate that this rib is of a fore-part (〜5th). This is the first record of the Order Sirenia from the Mandano Formation (including westward equivalent Nagahama Formation) of the upper Kazusa Group, and it represents the southernmost occurrence of the Steller's sea-cow in the world. The specimen also provides evidence that the Steller's sea-cow had distributed at least by the Middle Pleistocene in the adjacent sea around the Japanese Islands.
日本古生物学会の論文
1994-06-30