Definition of Proterozoic in English:

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Pronunciation: /ˌprəʊt(ə)rəˈzəʊɪk/


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.
Example sentences
  • 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.
  • This is the general name for all Archaean and Proterozoic basement gneisses of the NW Scotland mainland and Outer Hebrides.
  • The bulk of the Mozambique belt of eastern Africa and Madacascar is underlain by deeply eroded and multiply deformed high-grade Proterozoic and Archaean rocks.
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.


Late 19th century: from Greek proteros 'former' + zōē 'life', zōos 'living' + -ic.

For editors and proofreaders

Line breaks: Pro¦tero|zo¦ic

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