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The Bradoriida of the Niutitang Formation from Traditional Lower Cambrian in Jinsha County,Guizhou Province

YANG Xing-lian1,2, ZHU Ming-jin1, ZHU Lu-yan1, CUI Tao1   

  1. 1. College of Resource and Environment, Guizhou University, Guiyang 550003, China;2. State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology,Chinese Academy of Sciences, Nanjing 210008, China
  • Received:2009-09-20 Revised:2009-09-20 Online:2009-09-20 Published:2009-09-20

Abstract: Some Bradoriida fossils were preserved in the manner of carbonaceous membrane in black shale of the lower part of the Niutitang Formation of the traditional Lower Cambrian (Terreneuvian and Cambrian Series 2 ) in Zhangyangou Village, Yankong Town, Jinsha County, Guizhou Province. They include two genera, one species, one conformis species and one uncertain species as listed below : Kunmingella douville, Kunmingella sp. and Tsunyiella cf. luna. These bradoriid fossils were found in association with the oldest trilobite Tsunyidiscus( Mianxiandiscus), showing that their horizon is equivalent to the Abadiella Zone in Yunnan Province. Moreover, the lower horizon of Kunmingella and Tsunyiella may be correlated with the lower part of Qiongzhusian Stage. Kunmingella as an element in western palaeobiogeographical area and Tsunyiella as an element in middle palaeobiogeographical area appear together in Jinsha County belonging to the middle palaeobiogeographical area of early Cambrian bradoriids. Consequently, the range of mictium between the western and middle palaeobiogeographical area can be extend from Changning-Zhengxiong subdistrict to Jinsha and Zhijin Counties. The discovery of numerous bradoriid at the base of the Cambrian enriched the components of the Niutitang biota, and is of importance in studying the evolution of early organisms in Cambrian.