proterozoic eon meaning in Chinese
元古宙
Examples
- Global ice ages occurred at least three times in the period known as the proterozoic eon , first at 2 . 3 billion years ago and again at 750 million and 600 million years ago
原生代期间至少发生过三次全球性冰期，第一次始于23亿年前，其后于7 . 5亿与6亿年前又再度发生。