峡东地区早寒武世水井沱组古盘虫类三叶虫的再研究

RESTUDY ON THE EODISCOIDS FROM THE SHUIJINGTUO FORMATION (EARLY CAMBRIAN) IN EASTERN YANGTZE GORGE AREA, WESTERN HUBEI

对峡东和邻近地区早寒武世古盘虫类三叶虫的再研究 ,支持将EmeidiscusLi,1980 ;MianxiandiscusS .ZhangetZhuinZhangetal.,1980 ;Mianxiandiscus (Liangshandiscus)S .ZhanginZhangetal.,1980 ;HupeidiscusChanginLuetal.,1974 ;GuizhoudiscusS .ZhanginZhangetal.,1980 ;ShizhudiscusS .ZhangetZhuinZhangetal.,1980等属作为TsunyidiscusChang ,196 6的同义名的意见。并对前人所建立的有关属的种 ,进行了重新研究和整理 ,作了大量的归并和修订。就目前所知道 ,峡东地区早寒武世水井沱组的古盘虫类三叶虫仅有TsunyidiscusChang ,196 6和SinodiscusChanginLuetal.,1974两属。Hupeidiscus经修订归入TsunyidiscusChang ,196 6后 ,原HebediscusorientalisChang ,195 3(即原Hupeidiscus的模式种 )一种的种名与Tsunyidiscusorientalis (Walcott,190 5 )重名 ,故将前者重新命名为Tsunyidiscuspertenusnom .nov .。文中还记述了湖北宜昌、秭归等地的早寒武世古盘虫类三叶虫 2属 3种 ,包括TsunyidiscusyanjiazhaiensisS .Zhang ,ZhouetYuaninYinandLi,1978;Tsunyidiscusacutus (Sun ,1983) ;SinodiscuschangyangensisS .ZhanginZhouetal.,1977。

The eodiscoid material described in this paper was collected recently from the Lower Cambrian Shuijingtuo Formation in Yichang and Zigui of the Yangtze Gorge area, western Hubei by the present authors. It includes three species belonging to two genera and two families, namely, Tsunyidiscus yanjiazhaiensis S. Zhang, Zhou et Yuan in Yin et Li 1978,Tsunyidiscus acutus (Sun,1983),and Sinodiscus changyangensis S. Zhang in Zhou et al., 1977. In reviewing the eodiscoid genera from South China, the present authors concur with Jell (1997) in regarding Emeidiscus Li, 1980, Mianxiandiscus S. Zhang et Zhu in Zhang et al., 1980, Mianxiandiscus (Liangshandiscus) S. Zhang in Zhang et al., 1980, Hupeidiscus Chang in Lu et al., 1974, Guizhoudiscus S. Zhang in Zhang et al., 1980, Shizhudiscus S. Zhang et Zhu in Zhang et al., 1980 as junior synonyms of Tsunyidiscus Chang, 1966. We also agree to transfer Eodiscus chintingshanensis Lu, 1942 into Tsunyidiscus. The study on preservation and morphogical changes during ontogeny of the species assigned to above genera, and the examination on the type material of most previously described species at the Nanjing Institute of Geology and Palaeontology suggest a number of these species should be supperssed as junior synonyms or remain uncertain of specific assignment. As revised, Tsunyidiscus embraces only 10 valid species, whereas Sinodiscus includes only two species. These species and their synonyms are listed as follows: