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Related to Paleoproterozoic: Mesoproterozoic
Of, relating to, or being the oldest of the three eras of the Proterozoic Eon, from approximately 2.5 billion to 1.6 billion years ago, marked by the formation of stable continents and the appearance of cyanobacteria. See Table at geologic time.
The Paleoproterozoic Era.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.