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全球中奥陶统及奥陶系第三个阶、大坪阶的界线层型剖面和点位(GSSP)确定后,文中作者对宜昌黄花场剖面弗洛阶上部Oepikodus evae带牙形刺生物地层序列进行再研究。通过对红花园组上部-大湾组下段一些关键层位中牙形刺样品的补充采集和牙形刺标本的系统检查,研究牙形刺属种垂向分布特征,修订一些牙形刺属种的首现层位。讨论Stolodus stola,Lundodus gladiatus,Oepikodus intermedius,Oepikodus communis,Trape-zognathus diprion,Baltonioduscf.B.triangularis等重要的多分子器官种分类问题。识别出Baltoniodus trian-gularis(Lindstr m)的先驱:Baltonioduscf.B.triangularis(Lindstr m)与Baltoniodus triangularis(Lindstr m)的区别。描述新建化石带属种,包括Baltoniodus triangularis(Lindstr m)。认为Oepikodus evae带上部时限范围内并未见Oepikodus evae分子,所以与国际地层指南(2000)关于间隔带和延限带的含义相悖。据此,厘定了原Oepikodus evae带的含义。并以牙形刺带分子首现为标志,将大湾组下段自下而上划分为3个间隔带,分别为:O.evae带,Trapezognathus diprion带和Baltonioduscf.B.triangularis带。其中Trapezognathus diprion带和Baltonioduscf.B.triangularis带为新建化石带。
After the determination of the boundary layer profile and point (GSSP) of the third Middle Ordovician and Ordovician Member of the Middle Ordovician series and the Daping Stratum, the author analyzed the Oepikodus evae conodont sequence Re-study. The vertical distribution characteristics of the genus Polypodon were studied through the complement collection of conodont samples and the systematic examination of the conodonts in some key beds in the lower part of the Dahuayuan Formation of the Honghuayuan Formation. The first manifestation of the horizon. Discusses the important molecular species classification of Stolodus stola, Lundodus gladiatus, Oepikodus intermedius, Oepikodus communis, Trapezognathus diprion, Baltonioduscf. B.triangularis. The distinction between Baltonioduscf. B.triangularis (Lindstr m) and Baltoniodus triangularis (Lindstr m) was identified as a pioneer of the Baltoniodus trian-gularis (Lindstr m). Description New fossil species, including Baltoniodus triangularis (Lindstr m). The Oepikodus evae is considered to have no Oepikodus evae in the upper part of the band, which is contrary to the meaning in the International Stratigraphy Guideline (2000) concerning the interval and extension bands. Accordingly, determine the meaning of the original Oepikodus evae band. At the beginning of the conodont element, the lower part of the Dawan Formation was divided into three intervals, namely O.evae zone, Trapezognathus diprion zone and Baltonioduscf.B.triangularis zone. Trapezognathus diprion belt and Baltonioduscf.B.triangularis belt for the new fossil zone.