A series (443.7–449 Ma ago) of the Upper Ordovician, underlain by the Caradoc and overlain by the Llandovery (Silurian).
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。