- 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.
- the Proterozoic division of geologic time or the rock systems formed then; Algonkian.
Origin of Proterozoic
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for proterozoic
But how may we separate the Proterozoic rocks from the Archeozoic?
Similar forms are abundant in late Proterozoic strata of Montana.
This second series of rocks is called the Proterozoic (beginning of life) series, and marks a long age in the worlds history.The Outline of History: Being a Plain History of Life and Mankind
Herbert George Wells
Proterozoic , the age of invertebrate dominance, containing an early and a late ice age.Unexplored!</p>
Proterozoic fossils have been found in places where the present average temperature approaches 0°C.Climatic Changes
- the later of two divisions of the Precambrian era, during which the earliest plants and animals are assumed to have livedCompare Archaeozoic
- 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
Word Origin and History for proterozoic
Online Etymology Dictionary, © 2010 Douglas Harper
- 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.
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