寒武纪 Hánwǔjì Cambrian Origin Definitions Defs Strokes Stroke Words Sentences Sents 前寒武纪 qiánhánwǔjì Precambrian pre-Cambrian, the geological period before approximately 540 million years ago寒武纪大爆发 Hánwǔjìdàbàofā Cambrian explosion the Cambrian explosion寒武纪生命大爆发 Hánwǔjìshēngmìngdàbàofā Cambrian explosion the Cambrian explosion