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

对冲绳和久米岛的新近纪和第四纪沉积物进行了地层学和古生物学研究。野田、菊池和河原分别对与那原组和新里组的软体动物、海胆类和有孔虫进行了古生物学研究，确定了深海的优势和特征动物群。大多数深海软体动物群从与那原开始占主导地位，并在新里纪末期消失（MacNeiL, 1961, Noda, 1980, 1988, 1991, 1998），就像海胆动物群（Kikuchi 的研究）一样。 Thatcheria 的生物地理分布与 Teramachia 相似。 Phanerolepida表现出奇特的形态变异，与太平洋两岸的Teramachia表现出相似的分布。大多数深海软体动物是从与那原海峡出现的，并在新里海峡末端消失。 Kawagata 鉴定出了中新世晚期至上新世 Maja 组和 Aka 组的 112 种底栖有孔虫，并显示了沉积深度从 100 到 50 m 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.