寒武纪的早期。后跟中寒武世、晚寒武世。寒武纪是显生宙（Phanerozoic Eon)的开始，标志着地球生物演化史新的一幕。
早中寒武世 early-middle cambrian
This paper mainly gains following conclusions by this research.1. On the basis of the early study result as well as new rock stratum cleaning up mind, early Cambrian stratums in the Shandong region are studied completely.
通过本论文的研究，主要取得以下认识： 1、在大量前人研究成果的基础上，结合新的岩石地层清理意见，全面系统地对山东地区早寒武世地层进行了清理，主要将下寒武统划分为2阶：沧浪铺阶、龙王庙阶；3组：李官组、朱砂洞组、馒头组。
参考来源 - 山东地区早寒武世层序岩相古地理研究A study of these brachiopod fossils demonstrates that the Chengjiang Lagerstatte has the potential to elucidate the character acquisition and character evolution of brachiopod in the early Cambrian and to explore the earliest Phanerozoic diversification of Brachiopoda.
研究发现澄江化石库的腕足动物不但数量丰富、分异度较高，而且软体解剖信息保存异常丰富。 这些表明澄江化石库完全具有探索腕足动物早期分异、阐明早寒武世腕足动物性状获得和性状进化的潜力。
参考来源 - 澄江动物群腕足动物·2,447,543篇论文数据，部分数据来源于NoteExpress
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