Study on Triassic Smaller Foraminifers

在我们目前的研究之前，日本尚未对三叠纪有孔虫进行研究。我们试图从日本不同地区暴露的碳酸盐岩中收集到许多三叠纪较小的有孔虫。结果，我们发现了许多三叠纪有孔虫标本，出露于Menashidomari、Hidaka山脉和Kamiiso(北海道)、Ashio Mountain、Okutama地区和关东山脉的其他地区、Mino-Hida山脉的Akasaka石灰岩和其他石灰岩、四国和九州的Taho和Kamura石灰岩以及日本外带其他地方的其他未命名的小型碳酸盐岩区块。我们的藏品还包括泰国南部和马来西亚西北部的许多三叠纪碳酸盐岩。从北美太平洋一侧采集了一些标本，对这些标本进行了择优取向的薄片切片和/或经醋酸和氢氟酸处理后作为孤立标本回收，并进行了古生物学研究。这些室内工程尚未完成，但进展迅速。我们检查了之前描述的大部分三叠纪有孔虫，这些有孔虫主要是在欧洲国家引入的，包括瑞士、奥地利、意大利和Burgaria。共采集标本486种，初步列入今后的古生物调查，迄今已鉴定出约50种三叠纪有孔虫，分布于石灰岩至雷氏岩。甚至在下三叠统白云岩灰岩中也发现了一些原始类型的蛇纹石物种。中、上三叠统渐卷虫科和眼镜亚科的种类和属丰富多样。三叠纪有孔虫的演化趋势与珊瑚和海绵的演化趋势相似。

Previous to our present research, Triassic foraminifers have not yet been studied in Japan. We tried to collect many Triassic smaller foraminifers from carbonate rocks exposed in various areas in Japan. As the result, we discovered many specimens of Triassic foraminifers from carbonate rocks exposed in Menashidomari, Hidaka mountains, and Kamiiso (Hokkaido), Ashio Mountains, Okutama area and other areas of the Kanto Mountains, Akasaka Limestone and other limestones in the Mino-Hida Mountains, the Taho and Kamura Limestones of Shikoku and Kyushu, and other small unnamed carbonate rock blocks elsewhere in Outer Zone of Japan. Our collections also contain many Triassic carbonate rocks of southern Thailand and northwestern Malaysia. Some materials were collected from the Pacific Side of North America.These specimens are thin-sectioned in preferred orientation and/or recovered as isolated specimens by acetic acid and hydrofluoric acid treatment and paleontologically studied. These indoor works are not completed but rapidly progressing. We checked most of the previously described Triassic foraminifers which were introduced mainly in European countries including Switzerland, Austria, Italy, and Burgaria. The examined specimens attain 486 species and synoptically listed for our future paleontological investigation.Up to date, we already discriminated about 50 species of Triassic foraminifersfrom the Schytian to Rhaetian. Some primitive type of ammodiscusid species are found even in dolomitic limestone of the Lower Triassic. The species and genera of Involutinidae and Ophthalminiinae are abundant and diversified in the Middle to Upper Triassic. Evolutional tendency of Triassic foraminifers show similar pattern with that of scleractinian corals and sponges.