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Proterozoic

[prot-er-uh-zoh-ik, proh-ter-] /ˌprɒt ər əˈzoʊ ɪk, ˌproʊ tər-/ Geology
adjective
1.
noting or pertaining to the latter half of the Precambrian Era, from about 2.5 billion to 570 million years ago, characterized by the appearance of bacteria and marine algae; Algonkian.
noun
2.
the Proterozoic division of geologic time or the rock systems formed then; Algonkian.
Origin of Proterozoic
1905-1910
1905-10; protero- + zo- + -ic
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the Web for Proterozoic
Historical Examples
  • Hence, uplift alone cannot account for extensive glaciation in subtropical latitudes during the Permian and Proterozoic.

    Climatic Changes Ellsworth Huntington
  • Similar forms are abundant in late Proterozoic strata of Montana.

    Geology William J. Miller
  • But how may we separate the Proterozoic rocks from the Archeozoic?

    Geology William J. Miller
  • Proterozoic fossils have been found in places where the present average temperature approaches 0°C.

    Climatic Changes Ellsworth Huntington
  • This second series of rocks is called the Proterozoic (beginning of life) series, and marks a long age in the worlds history.

  • We shall now turn our attention briefly to a consideration of the second great subdivision of geologic time—the Proterozoic era.

    Geology William J. Miller
  • Proterozoic , the age of invertebrate dominance, containing an early and a late ice age.

    Unexplored! Allen Chaffee
  • Thus, igneous rocks distinctly predominate in the Archeozoic, while stratified rocks predominate in the Proterozoic.

    Geology William J. Miller
  • The later Proterozoic strata have been much less deformed and in many cases they are practically unaltered.

    Geology William J. Miller
  • Why are the very early Paleozoic strata so rich in fossils, while the immediately preceding Proterozoic rocks show so few?

    Geology William J. Miller
British Dictionary definitions for Proterozoic

Proterozoic

/ˌprəʊtərəʊˈzəʊɪk/
noun
1.
the later of two divisions of the Precambrian era, during which the earliest plants and animals are assumed to have lived Compare Archaeozoic
adjective
2.
of or formed in the late Precambrian era
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for Proterozoic
adj.

1880, from protero- + zoic.

Online Etymology Dictionary, © 2010 Douglas Harper
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Proterozoic in Science
Proterozoic
  (prŏt'ər-ə-zō'ĭk)   
The later of the two divisions of the Precambrian Eon, from about 2.5 billion to 540 million years ago. The Proterozoic was characterized by the formation of stable continents, the appearance of abundant bacteria and archaea, and the buildup of oxygen in the atmosphere. By about 1.8 billion years ago the oxygen buildup was significant enough to cause many types of bacteria to die out. At this time eukaryotes, including multicellular algae and the first animals, first appear in the fossil record. See Chart at geologic time.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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