广西六景中泥盆统民塘组底部的硅化腕足动物化石

The silicified brachiopod fossils from the base of the Mintang Formation (Middle Devonian) in Liujing,Guangxi

笔者系统研究了广西六景中泥盆统民塘组底部的硅化腕足化石，描述了３１个属种，其中新属、新亚属各１个，新种２０个，划分出Ｇｅｒａｎｏｃｅｐｈａｌｕｓ－Ｐｅｎｔａｍｅｒｅｌａ（下部）动物群和Ｓｔｒｉｎｇｏｃｅｐｈａｌｕｓ－Ｃｈａｎｇｔａｎｅｌａ（上部）两个动物群。着重对Ｇｅｒａｎｏｃｅｐｈａｌｕｓ－Ｐｅｎｔａｍｅｒｅｌａ动物群的特征与时代进行了讨论，其时代具浓厚的艾菲尔晚期的色彩。该动物群属老世界区的一部分，与美国内华达同期动物群有密切的亲缘关系，同时与欧洲（如德国、捷克以及乌拉尔地区）也有一定相似性，然而从种群而言，它是一个斩新的动物群。提出Ｇｅｒａｎｏｃｅｐｈａｌｕｓ不是Ｓｕｂｒｅｎｓｅｌ－ｌａｎｄｉａ与Ｓｔｉｎｇｏｃｅｐｈａｌｕｓ之间的中间形态，而是Ｒｅｎｓｅｌａｎｄｉａ与Ｓｔｉｎｇｏｃｅｐｈａｌｕｓ之间的中间形态，很可能Ｇｅｒａｎｏｃｅｐｈａｌｕｓ就是Ｓｔｉｎｇｏｃｅｐｈａｌｕｓ的先躯，它代表Ｒｅｎｓｓｅｌａｎｄｉａ向Ｓｔｉｎｇｏｃｅｐｈａｌｕｓ演化过程中的一个重要阶段。

The present paper deals in detail with the silicified brachiopod fossils from the base of the Mintang Formation (Middle Devonian) in Liujing,Guangxi.Thirty one genera and species,including one new genus,one new subgenus and twenty new species are described,resulting in the establishment of two faunas Geranocephalus Pentamerella(lower)and Stringocephalus Changtanella(upper).In particular,the studies of the characteristics and geological ages of the fauna Geranocephalus Pentamerella indicate that the fauna is likely to be late Eifelian in age,and thus may be ascribed to a part of the Old World Province.It also has a close affinity to the coeval faunas in Nevada,U.S.A.,or displays the striking similarities to those from Europe(e.g.Germany,Czech and Ural).The author argued,however,that it is indeed a new fauna.The fauna Geranocephalus should not be an intermediate type between Subrenssellandia and Stingocephalus but the one between Renssellandia and Stingocephalus;probably it should be the precursor of Stingocephalus,and represents an important stage in the transition from Renssellandia to Stingocephalus.