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Title :日本の中生代汽水生二枚貝化石群に関する研究の現状 : 天草地域の白亜系から産出する二枚貝の生息域とジュラ紀〜白亜紀マガキ類の古生態について(<特集>干潟の自然,その過去と現在)
Authors :小松, 俊文
Issue Date :22-Sep-2004
Citation jtitle :化石
no. :76
start page :76
end page :89
Abstract :Several issues in the methods of reconstructing paleoecology of the Mesozoic brackish-water bivalves, the contents of the bivalve assemblages and their paleoenvironments in Japan are discussed. The brackish-water environments can be reconstructed as shallow marine environments associated with fluvial systems on the basis of facies analysis. Paleoecology of bivalve fossils is inferred from their modes of occurrence in each depositional environment. Here, descriptions are given for two examples of paleoecologic analysis of the Mesozoic bivalve faunas : (1) Comparisons between the "mid"-Cretaceous Goshoura Group and the Upper Cretaceous Himenoura Group ; both groups are characterized by brackish-water-influenced tidal flat deposits containing abundant true oyster (Crassostrea). Infaunal bivalves of the "mid"-Cretaceous assemblage are characterized by neomiodontids, although those of the Upper Cretaceous assemblage are represented by venerids. (2) Another example is the taxonomy and paleoecology of the Upper Jurassic to Cretaceous primitive Crassostrea. These oysters are ecologically similar to recent Crassostrea, but compared with recent species, shell sizes of the Upper Jurassic and Lower Cretaceous materials are small. Their shell structures are characterized by poorly developed chambers and chalky deposits, which suggest more archaic conditions.
URL :http://ci.nii.ac.jp/naid/10017457743
Type Local :雑誌掲載論文
Publisher :日本古生物学会
Rights :日本古生物学会
Comment :本文データは学協会の許諾に基づきCiNiiから複製したものである
URI :http://hdl.handle.net/2298/18735
Appears in Collections:Journal Article (Sciende)
Please use this identifier to cite or link to this item: http://hdl.handle.net/2298/18735