A stage of the Upper Cambrian, underlain by the Late Cambrian, preceded by the Middle Cambrian, followed by the Festiniogian, and dated at 501–496.8 Ma ago (Int. Commission on Stratigraphy, 2004).
科学参考收录了60776条科技类词条，基本涵盖了常见科技类参考文献及英语词汇的翻译，是科学学习和研究的有利工具。