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Article type: Cover
1982 Volume 31 Pages
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Published: June 21, 1982
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Article type: Appendix
1982 Volume 31 Pages
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Article type: Index
1982 Volume 31 Pages
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Article type: Appendix
1982 Volume 31 Pages
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Tatsuro Matsumoto, Ikuwo Obata, Masayuki Tashiro, Yoshihisa Ohta, Mino ...
Article type: Article
1982 Volume 31 Pages
1-26
Published: June 21, 1982
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In various areas of Japan, non-marine sediments (s.l.) of fluviatile, lacustrine, and brackish-water environments are frequently interfingered with marine ones which contain index species of ammonites and other groups. Therefore, the geological age of the former can be determined by that of the latter in terms of the international scale. The result of the correlation on available evidence is shown in three charts (Figs. 1-3), in which ammonites, other marine biota, brackish-water fauna, fresh-water fauna and land-plants are also stratigraphically allocated. Outside the scope of the three charts, the biostratigraphically well subdivided marine sequences of Hokkaido and the Campanian-Masstrichtian sequences of Southwest Japan do contain transported remains (petrified woods, seeds, leaves, pollen and spores) of land-plants in favourable preservation, whose geological ages can also be determined in terms of international scale. On the ground of these results, the evolutionary history of the non-marine faunas and floras can be studied precisely. This would in turn be a foundation for the correlation of the continental deposits in Eastern Asia. This paper is a contribution to the IGCP Project No.58 Mid-Cretaceous Events [MCE].
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Kiyotaka Chinzei
Article type: Article
1982 Volume 31 Pages
27-34
Published: June 21, 1982
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Some paleoecologic aspects of oysters are discussed, giving special emphasis on the adaptive strategy of Crassostrea to the soft muddy bottom. Crassostrea is most abundant in the muddy intertidal facies despite their sessile and suspension feeding habit. Muddy bottom environment seems unfavorable for oysters because it offers very few basis of attachment, and gives continuous danger of suffocation by rapidly accumulating mud. Crassostrea surmounts these difficulties in living on mud, and becomes dominant in this environment. The basic strategy of Crassostrea for the survival in the muddy bottom is considered to be their gregarious tendency to constitute the densely aggregated colony. The colony supports the individual shell to stand above the surface of mud, and gives the firm basis for the attachment of later generations. The later generations grow on the colony, thus manage to keep living animals atop the rising mud level. Formation of the biohermal reef is the consequence of this characteristic behavior of Crassostrea. Nongenetic variations in shell morphology are conspicuous among Crassostrea individuals. The shell outline of fossil and living Crassostrea gigas is not controlled by the population density, but is probably related to the position of the shell : individuals in the upright position tend to be elongated irrespective of their density, and those lying on the bottom are usually more rounded. The population density apparently affects the individual shell size. Where the density is low, shells are very large, while they are small in densely populated reefs. The relationship may be explained by the competitive effect in the allocation of limited food supply.
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Teiichi Kobayashi
Article type: Article
1982 Volume 31 Pages
35-39
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[in Japanese]
Article type: Article
1982 Volume 31 Pages
40-
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[in Japanese]
Article type: Article
1982 Volume 31 Pages
40-
Published: June 21, 1982
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Palaeontological Soiciety of Japan, Committee on Research Institution ...
Article type: Article
1982 Volume 31 Pages
41-46
Published: June 21, 1982
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Koichiro Masuda
Article type: Article
1982 Volume 31 Pages
47-49
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[in Japanese]
Article type: Article
1982 Volume 31 Pages
50-
Published: June 21, 1982
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[in Japanese]
Article type: Article
1982 Volume 31 Pages
50-
Published: June 21, 1982
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[in Japanese]
Article type: Article
1982 Volume 31 Pages
50-
Published: June 21, 1982
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[in Japanese]
Article type: Article
1982 Volume 31 Pages
50-
Published: June 21, 1982
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[in Japanese]
Article type: Article
1982 Volume 31 Pages
50-
Published: June 21, 1982
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[in Japanese]
Article type: Article
1982 Volume 31 Pages
50-
Published: June 21, 1982
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[in Japanese]
Article type: Article
1982 Volume 31 Pages
50-
Published: June 21, 1982
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[in Japanese]
Article type: Article
1982 Volume 31 Pages
50-
Published: June 21, 1982
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[in Japanese]
Article type: Article
1982 Volume 31 Pages
50-
Published: June 21, 1982
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[in Japanese]
Article type: Article
1982 Volume 31 Pages
50-
Published: June 21, 1982
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[in Japanese]
Article type: Article
1982 Volume 31 Pages
51-52
Published: June 21, 1982
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Article type: Appendix
1982 Volume 31 Pages
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Article type: Cover
1982 Volume 31 Pages
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Article type: Cover
1982 Volume 31 Pages
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