早期原附栉虫类三叶虫在唐山地区的发现及其一些属种的修订

Discovery of early proasaphiscid trilobites in Tangshan area,North China,and revision of some genera and species

本文对产于云南曲靖龙王庙剖面和贵州丹寨南皋三湾及曾经报道过的湄潭等地剖面中含有早期原附栉虫类三叶虫的一些模式标本和属种原产地的地模标本进行了重新采集和厘定研究,并首次研究报道了来自华北地台区河北唐山馒头组中的早期原附栉虫类三叶虫。通过对个体发育中异速发育特征进行的简要分析,提出了用鞍前区与头鞍长度的相对比例大小和肋沟和间肋沟向尾边缘延伸的情况来区分Kuetsingocephalus和Danzhaiaspis两属,总结了二者的系统分类与鉴别特征,确认这两个属的可靠分类地位和生物地理古分布,并再次证实了Kuetsingocephalus kuetsingensis这个以往被认为只产在扬子浅水地台区的分子也能扩散到深水斜坡相区。根据华北的新材料建立了原附栉虫类1新属和3新种:Qizuoshania tangshanensis gen.et sp.nov.,Danzhaiaspis intermedius sp.nov.,Kuetsingocephalus fengrunensis sp.nov.,显示以往仅在扬子地台区的Danzhaiaspis,Kuetsingocephalus也见于华北地台区。说明在没有掘头虫类三叶虫的情况下,由于早期原附栉虫类分布广、演化快,其在华北地台区和扬子地台区的寒武纪第二统和苗岭统界线划分问题上的重要性。

This study of proasaphiscid trilobites is based on some type specimens and new materials(topotypes)collected from the type sections at Longwangmiao,Qujing in eastern Yunnan as well as at Sanwan,Nangao,Danzhai,Kaili and Meitan in Guizhou.The diagnoses and occurrences of Kuetsingocephalus and Danzhaiaspis have been revised,and the ratio of preglabellar field to glabellar length is here considered as the main crucial distinction between the two genera.In Kuetsingocephalus the ratio of preglabellar field to glabellar length is less than 24%,but in Danzhaiaspis it is more than 30%.In Danzhaiaspis all pleural ribs are visible,while in Kuetsingocephalus only the first pair of pleural ribs is visible.One new genus and three new species have been established herein:Qizuoshania tangshanensis gen.et sp.nov.,Danzhaiaspis intermedius sp.nov.,and Kuetsingocephalus fengrunensis sp.nov.With exception of oryctocephalids,the proasaphiscid trilobites are of very important significance for defining the boundary of Cambrian Series 2 and Miaolingian Series in North China Platform and the Yangtze Platform owing to its wide distribution and rapid evolution in China.