国内多数研究者均将华北峰峰组与本区中奥陶统对比。近年来笔者等发现,本区早中奥陶世牙形刺动物群面貌显著不同,峰峰组 Badoudus-Panderodus-Microcoelodus 牙形刺组合,出现于本区南缘歧山、泾阳、富平一带下奥陶统顶部的石马坪组之中,且与整个下奥陶统牙形刺动物群同属太平洋型。其上则整合覆以含北大西洋型牙形剌组合的 Most domestic researchers compare the North China Fengtai Formation with the Middle Ordovician in this area. In recent years, the authors found that the area of ​​the Early Middle Ordovician conodont was significantly different in this area. The combination of Badoudus-Panderodus-Microcoelodus condyloma in the Feng-feng Formation occurred in the lower Ordovician of Qishan, Jingyang, Fuping, At the top of the Shima Ping Group, and with the entire Lower Ordovician toxoptera fauna belong to the Pacific. Its integration is covered by a combination of North Atlantic condylar