Dictionary
Prot•er•o•zo•ic
Pronunciation: (prot"ur-u-zō'ik, prō"tur-), [key] Geol.
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adj.
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.
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n.
the Proterozoic division of geologic time or the rock systems formed then; Algonkian. See table under
geologic time. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.