Origin and route of the Neogene deep sea molluscan fauna in Ryukyu Islands

对冲绳和久米岛新近纪和第四纪沉积物进行了地层学和古生物学研究。根据Noda、菊池和Kawagara分别对米原组和新里组的软体动物、棘虫和有孔虫的古生物学研究，确定了米原组和新里组的优势和特征深海动物群。大多数深海软体动物群从与那原开始占优势，并在新座末期消失（MacNeiL，1961，Noda，1980，1988，1991，1998），就像海胆动物群一样（菊池的研究）。Thatcheria与Teramachia的地理分布相似。在太平洋两岸的分布上，石足类与Teramachia类有相似的特征。大部分深海软体动物出现在与那原，消失在新里的尽头。Kawagata在晚中新世至上新世Maja组和Aka组共鉴定出112种底栖有孔虫，并显示出它们沉积深度从100米到50米的水深变化。

The stratigraphy and paleontology of the Neogene and Quarternary deposits in Okinawa and Kume-jima were examined. According to paleontological studies on the molluscs, echinoids and foraminifers from the Yonabaru and Shinzato Formations by Noda, Kikuchi and Kawagara, repectively, the dominant and characteristic deep sea faunas were recognized. Most of deep sea molluscan faunas become dominant from the Yonabaru and were disappeared at the end of the Shinzato (MacNeiL, 1961, Noda, 1980, 1988, 1991, 1998) as like the echinoid faunas (Kikuchi's research). Thatcheria shows similar biogeographical distribution with that of Teramachia. Phanerolepida shows peculiar morphological variation and shows similar distitribution with that of Teramachia on both sides of the Pacific. Most of deep sea mollsucs had been appeared from the Yonabaru and disappeared at the end of the Shinzato. A total of 112 species of benthic foraminifers from the late Miocene to Pliocene Maja and Aka Formations were identified by Kawagata and show the bathymetric changes from 100 to 50 m in their depositional depth.