Possibly one of the earliest jawless fish, known from a number of associated scales and fragments discovered in Lower Ordovician (Arenig) strata at Spitzbergen.
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。