贵州剑河八郎“清虚洞组”Protoryctocephalus Chow(Zhou) in Lu et al.,1974b的初步研究

A PRELIMINARY STUDY OF PROTORYCTOCEPHALUS CHOW(ZHOU) IN LU ET AL.,1974B FROM THE CAMBRIAN “TSINGHSUTUNG FORMATION” OF GUIZHOU,CHINA

三叶虫掘头虫科古掘头虫属Protoryctocephalus Chow(Zhou)in Lu et al.,1974b由周志毅根据贵州丹寨南皋寒武系乌训组的标本命名,至今共有4个种:Protoryctocephalus wuxunensis,P.balangensis,P.elongatus,P.arcticus。贵州剑河八郎"清虚洞组"产其中的2个种:P.elongatus及P.arcticus。P.elongatus首现于"清虚洞组"上部,上延至凯里组下部;P.arcticus命名于格陵兰北部Peary Land的Henson Gletscher组中部,位于寒武系第5阶首现分子Oryctocephalus indicus层位之下,为格陵兰北部Peary Land的Henson Gletscher组与凯里组下部及"清虚洞组"上部的地层对比提供了化石依据,有助于寒武系第5阶地层对比。八郎"清虚洞组"P.elongatus及P.arcticus的发现具有演化及国际地层对比意义。

The trilobite Protoryctocephalus Chow （Zhou） in Lu et al. , 1974b was named by Zhou Zhi-yi, based on the specimens from the Cambrian Wuxun Formation of Danzhai, Guizhou Province. Up to now, four species have been documented in this genus, including Protoryctocephalus wuxunensis, P. balangensis, P. elongatus and P. arcticus. Both P. elongatus and P. arcticus are yielded in ＂Tsinghsutung Formation＂ at Songshan Section, Balang Village, Guizhou Province. P. elongatus appears at the top of the ＂Tsinghsutung Formation＂, extending to the lower part of the Kaili Formation. P. arcticus named in the Henson Gletscher Formation, North Greenland is under the FAD of Oryctocephalus indicus of the Cambrian Stage 5, which provides evidence for statigraphic correlation between Henson Gletscher Formation and the top of the ＂Tsinghsutung Formation＂, and also contributes to the study of Cambrian Stage 5. The discovery of P. elongatus and P. arcticus implies evolutionary significance and provides evi- dence for biostratigraphic correlation on evolution and stratigraphic correlation.