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

关键词:  硅化腕足动物  中泥盆统  民塘组  六景  广西

Key words:  silicified brachiopod fossil  Middle Devonian  Mintang Formation  Liujing.Guangxi

摘要:

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-Pentamerella(下部)动物群和Stringocephalus-Changtanella(上部)两个动物群。着重对Geranocephalus-Pentamerella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Subrenssel-landia与Stingocephalus之间的中间形态,而是Rensselandia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。

Abstract:

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 interme-diate 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.