index fossil
noun [ C ] geology specialized uk/ˈɪn.deks ˌfɒs.əl/ us/ˈɪn.deks ˌfɑː.səl/
标准化石
a fossil that is found in many places and comes from the same time in history, so that scientists can use it to decide how old certain rocks are
江苏热线英汉汉英双解词典包含207361条英汉翻译词条，涵盖了常用英语单词及词组短语的翻译及用法，是英语学习的必备工具。