湖北宜昌地区晚奥陶世三叶虫动物群及分带序列

从湖北宜昌黄花场和普溪河桥宝塔组剖面获得的新材料,极大地丰富了华南晚奥陶世三叶虫动物群内容,包括22属、1亚属、31种之多。新材料保存完美,很大程度上完整了有关三叶虫的形态特征。RemopleuridesamphitryonoidesLu,1975一种由于新发现了活动颊、唇瓣、胸部及尾部,证明它确实是Remopleurides的成员,排除了对该种归属的怀疑。文中建立了1新属和2新种:Pentacopygepuxiheensisgen.etsp.nov.,Lamproscutellum?limbatumsp.nov.。同时,以桨肋虫类为基础在宝塔组Nankinolithus带之下进一步划分出4个三叶虫带,从下到上依次为Pentacopygepuxiheensis间隔带,Hexacopygeyichangensis间隔带,Remopleuridesamphitryonoides延限带(普溪河段,卡拉道克中期),和Dislobosaspisguizhouensis延限带(临湘段下部,卡拉道克晚期)。

LATE ORDOVICIAN TRILOBITE FAUNA AND SUCCESSION, YICHANG, HUBEI PROVINCE, CHINA

The new material described in this paper was collected from two measured sections through the Puxihe Member and Linxiang Member of the late Ordovician Pagoda Formation at Huanghuachang and Puxiheqiao, Yichang County (Text-figs. 1-3), including 31 trilobite species assigned to 22 genera and 1 subgenus. Among them one genus and two species are new, viz., Pentacopyge puxiheensis gen. et sp. nov. and Lamproscutellum? limbatus sp. nov., and following 11 forms are recorded for the first time in the Yichang area: Amphitron sp. 1, A. sp. 2, Cyclopyge recurva Lu, Decoropro-etus sp., Dislobosaspis guizhouensis (Yin), Madygenia snavis Petrunina, Microparia (Microparia) cf. speciosa (Hawle and Corda), Ovalocephalus kanlingensis (Zhang), O. yichongqiaoensis (Wu and Xia), Paraphillipsinella nanjiangensis Lu, Trinodus cylindricus Chen. The species Remopleurides amphitryonoides Lu, 1975 that was reassigned by Nikolaisen (1982) to the genus Sculptella Nikolaisen is here considered as a real member of Remopleurides on the basis of characters of the associate librigena, hypstome, thorax and pygidium. Except for the well-known Nankinolithus As semblage Zone (early Ashgill) that represents the uppermost horizonsof the Linxiang Member, no other reliable trilobite zones has been established for the Pagoda Formation in the Yichang area before. Four new additional remopleuridids-based biozones are, therefore, here suggested for the main part of the Pagoda Formation, in ascendingorder, the Pentacopyge puxiheensis Interval Zone, Hexacopyge yichangensis Interval Zone, Remopleurides amphitryonoides Range Zone (middle Caradoc:Puxihe Member),and the Dislobosaspis guizhouensis Range Zone(late Caradoc: lower part of the Linxiang Member).