贵州松桃寒武系第二统清虚洞组腕足动物 Eohadrotreta zhenbaensis的发现

微型腕足动物化石镇巴始壮贝Eohadrotreta zhenbaensis常见于陕南、峡东水井沱组与黔东麻江九门冲组等地寒武纪地层中,在贵州松桃盘信寒武系第二统清虚洞组薄层灰岩中为首次发现。通过与华南其他地区E. zhenbaensis的背壳长宽比及中隔板等结构特征比较,发现松桃盘信清虚洞组E. zhenbaensis与浅水扬子地台的陕南、峡东地区的E. zhenbaensis壳体内部特征较为相似,包括肉茎孔形成阶段、肉茎孔封闭阶段及交互沟伸长阶段3个生长发育阶段标本,与较深水过渡区麻江的E. zhenbaensis略有差异。贵州松桃盘信寒武系第二统清虚洞组E. zhenbaensis的发现,扩展了该属化石在华南寒武纪第二世的古地理分布,丰富了该组腕足动物组成面貌,为研究E. zhenbaensis形态结构特征提供了新材料。

THE DISCOVERY OF EOHADROTRETA ZHENBAENSIS (BRACHIOPODA) FROM THE CAMBRIAN SERIES 2 TSINGHSUTUNG FORMATION OF SONGTAO, GUIZHOU

Micro-brachiopod Eohadrotreta zhenbaensis has been constantly reported in Cambrian Series 2 of South China, such as the Shuijingtuo Formation of southern Shaanxi Province, western Hubei Province and Jiumenchong Formation of east Guizhou Province. Herein, for the first time, we report a large number of E. zhenbaensis collected from the thin limestone of the Cam-brian Stage 4 Tsinghsutung Formation at the Panxin section in Songtao County of Guizhou Province. The specimens of E. zhenbaensis from the Tsinghsutung Formation include the whole 3 development stages, pedicle foramen forming stage, pedi-cle foramen enclosing stage and intertrough increasing stage. The morphological characteristics of E. zhenbaensis reported herein are more similar to the specimens from the Shuijingtuo Formation of southern Shaanxi and western Hubei in the shal-low Yangtze platform, but they are slightly different from these from the Jiumenchong Formation of east Guizhou in slightly deep water slope. In short, the discovery of the E. zhenbaensis from the Cambrian Series 2 Tsinghsutung Formation at Panxin section further expands its paleogeographic distribution of this genus during Cambrian Epoch 2 in South China, which can also enrich the brachiopod assemblages from the Tsinghsutung Formation, and provide new material for the study of the morphologic variations of E. zhenbaensis.