東亜の古生代こけ虫化石の研究

抄録

I. Outline of historical reviews
The Paleozoic bryozoan researches in Asia were introduced after the 20th century except for the reported from the Salt Range bryozoan fauna which was described by WAAGEN and PICHL (1885), and WAAGEN and WENTZEL (1886). In East Asia, although there are some pioneered works on the Paleozoic bryozoans by MANSUY (1912, 1913), YABE and HAYASAKA (1920), NEWTON (1926), REED (1927), YOH (1932), OZAKI (1933), YABE and SUGIYAMA (1942) and so on, they were not systematic studies of Bryozoa.
The Paleozoic bryozoan studies in East Asia were earnestly made since 1950, namely, in China by YANG, Loo, Hu, HSIA, LIU, LI ; in Altai and Siberia of USSR. by NEKHOROSHEV, TRIZNA, ASTROVA, MODZALEVSKAYA, ROMANTCHUK and MOROZOVA ; in Japan and Southeast Asia by SAKAGAMI and SUGIMURA.
II. Study of Paleozoic bryozoans in Japan
Generally the Silurian-Devonian bryozoans in Japan are ill-preserved and rare, and only one species of the Silurian bryozoan : Monotrypella? yabei has been hitherto described by SUGIYAMA (1944) from the middle Silurian of Japan. Recently, some materials, however, were collected from the Kitakami and Hida massifs. They are Stereotoechus Kitakamiensis (n. sp., MS) and some fenestellids from the middle Devonian of the Kitakami massif, and Eridotrypella? sp. (probably n. sp., MS), Fenestella sp. indet. and Sulcoretepora sp. indet. from the Devonian of the Hida massif. They will be described paleontologically in the near future. The Carboniferous-Permian bryozoans in Japan have been summarized by SAKAGAMI (1967b, 1970a). Later, SUGIMURA and OTA (1971), SUGIMURA (1972, 1974), and SAKAGAMI and SUGIMURA (1978) studied some Upper Paleozoic bryozoans from the Akiyoshi limestone.
III. Study of Paleozoic bryozoans in China
Recently, its Paleozoic bryozoan studies have been greatly progressed by the efforts of YANG, K. C. and his collaborators. At present, 440 species of the Paleozoic bryozoans have been described and illustrated as shown in Table 1.
IV. Study of Paleozoic bryozoans in Southeast Asia
The Silurian and Devonian bryozoans from Indo-China are very poor and insufficient for comparison with those of other areas, however, the “Anthracolithic” bryozoan fauna, in spite of small one, contains the European and/or Salt Range elements. The further studies should be expected.
On the other hand, our knowledge of the Paleozoic bryozoan fauna from the Thai-Malayan district has much progressed in this decade by SAKAGAMI (1963-). At present, about 30 species of the Carboniferous and more than 90 species of the Permian bryozoans have been described from 16 localities in the Thai-Malayan district. Generally these bryozoan faunas constitute a unique assemblage but contain both European and Asian elements among its genera.
V. Comparison of Paleozoic bryozoan facies between Japan, China and Southeast Asia
Table 2 shows the distributions of the bryozoan genera in East Asia. As shown in Table 3, total numbers of bryozoan genera in each Period are gradually increased to the younger, but it is different from the world-wide tendency.
The most world-wide genera in the Paleozoic Group, i. e., Fistulipora, Fenestella and Polypora are known abundantly also in East Asia. They are known from the Ordovician to Permian, but are extremely rare in the Ordovician and Silurian. Thus, there seems to be a large change of the Paleozoic bryozoan facies between the Silurian and Devonian. On the other hand, in East Asia, the common genera between the Devonian and Carboniferous bryozoan faunas are only 8 and a considerable change between them is recognized. There are 20 common genera between the Carboniferous and Permian faunas, and their relationship between two faunas seems to be successive.