单词 | Proterozoic |
释义 | Proterozoic/ˌprəʊt(ə)rəˈzəʊɪk /adjective Geology 1Relating to or denoting the aeon that constitutes the later part of the Precambrian, between the Archaean aeon and the Cambrian period, in which the earliest forms of life evolved.No rock standard has been identified formally as marking the base; at the top of the Proterozoic the Cambrian - Precambrian boundary is identified on the basis of fossils....
1.1 (as noun the Proterozoic) The Proterozoic aeon or the system of rocks deposited during it. The Proterozoic lasted from about 2,500 to 570 million years ago. For millions of years only bacteria and single-celled organisms existed, and the early invertebrates that followed were soft-bodied and rarely left any trace in the form of fossils. OriginLate 19th century: from Greek proteros 'former' + zōē 'life', zōos 'living' + -ic. |
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