广西西湾煤矿早侏罗世双壳类化石

    EARLY JURASSIC BIVALVE FOSSILS FROM THE XIWAN COAL MINE, GUANGXI

    • 摘要: 文中描述的双壳类化石,系笔者(姚培毅)于1984年4月赴广西桂东北部钟山县西湾煤矿进行地质调查时,在下侏罗统大岭组中部灰黑色灰岩中所采获。经鉴定,共计1属5种,名单如下:Qiyangia loxos,Q.fortis,Q.lilingensis,Q.cuneata,Q.of.loxos。过去对这里所产的双壳类化石,极少正式报导。迄今为止,仅见有不够系统的化石鉴定名单(陈金华等,1980a),未见描述和图影。因此,我们认为有必要予以报导。尽管当前标本类型较单调,但其数量丰富,保存尚好。

       

      Abstract: This paper describes the Early Jurassic non-marine bivalve fossils collected from the Daling Fromation at Xiwan, Zhongshan county, Guangxi. These bivalves were found in a bed of black limestone, about 62 m thick. The fossils include one genus and five species as listed below: Qiyangia loxos, Q. fortis, Q. lilingensis, Q. cuneata and Q. cf. loxos. The microstructure of Qiyangia shells has also been preliminarily studied. The shell structure of Qiyangia is described below: test about 14 mm thick: lenticular nacre well developed, about 10 mm thick; it consists of nacre tablets regularly arranged, and bended upwards, paralle to the growth line, downwards at an angle of 40-45 to the sheet nacre (about 3 mm thick). There are more sheets of organic matrix in the sheet nacre, but conchiolin layers within the nacre are not seen. This genus differs from Margaritifera and Unio in having thicker lenticular nacre, more bens, thicker sheet nacre and no conchiolin sheet. Judging by the macrostructure and microstructure of Qiyangia. the authors consider that it is right to set up a genus and it is temporarily ascribed to Unionidae.

       

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