房総半島の鮮新統名洗層から産出したコブオウギハクジラとその生存レンジについて

概要

論文の詳細を見る
The rostral fragment belonging to the large-mesorostral beaked whale, Mesoplodon tumidirostris Miyazaki & Hasegawa, 1992, was described from the Lower Pliocene Basal Conglomerate Bed of the Na-arai Formation (Ozaki, 1954) on the Boso Peninsula, central Japan. The new material from the Naarai Formation has large mesorostral ossification or supravomerine with a huge lump occupying the midline of the dorsal surface on the posterior part of the rostrum, which is slightly slanted to the right side at its posterior part. These characters are identical with those of M. tumidirostris known so far from ocean bottom near Hawaii Islands. Because the geologic age of the type material of M. tumidirostris is uncertain, the new occurrence of this species from the Lower Pliocene Na-arai Formation represents the first record from which the geochronological distribution of M. tumidirostris can be taken. Mesoplodon tumidirostris lived in deep sea at least around the Japanese Islands during the Early Pliocene (ca. 5.3-3.6 Ma) and might existed also from the low to middle latitudes in the North Pacific at that time.
国立科学博物館の論文
2002-12-25