Relating to or denoting the eon that constitutes the later part of the Precambrian, between the Archean eon and the Cambrian period, in which the earliest forms of life evolved.‘Proterozoic rocks occur in all the great Precambrian cratons of the world’
- ‘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.’
- ‘Archean and most Proterozoic sedimentary rocks are notable for their distinct lack of any bioturbated textures.’
- ‘The key to understanding the early evolution of eukaryotes lies in the Proterozoic fossil record, especially microfossils.’
the ProterozoicThe eon that constitutes the later part of the Precambrian, between the Archean eon and the Cambrian period, or the system of rocks deposited during it.
The Proterozoic lasted from about 2,500 million 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
- ‘we know very little of the geography of the Proterozoic’
Late 19th century from Greek proteros ‘former’ + zōē ‘life’, zōos ‘living’+ -ic.