Definitions
from The American Heritage® Dictionary of the English Language, 5th Edition.
- adjective Of, relating to, or being the most recent of the two divisions of Precambrian time, from about 2.5 billion to 542 million years ago, marked by the formation of stable continents, the buildup of oxygen, and the appearance of the first multicellular eukaryotic life forms.
- noun The Proterozoic Eon.
from The Century Dictionary.
- Of or pertaining to the life existing before the time of the Cambrian or first fossils: a term originally proposed as a substitute for Azoic, Eozoic, Archæan, etc., in order to avoid the assertions contained in these words if taken literally.
- noun The time during which the simplest life-forms were developed: applied to the interval between the Archeozoic and Paleozoic as used by Chamberlin and Salisbury. It is assumed that life existed, but no determinable forms have yet been found. The subdivisions of the Proterozoic are Keweenawan, Animikean, and Huronian.
from Wiktionary, Creative Commons Attribution/Share-Alike License.
- adjective geology Of, or relating to the
geologic eon from about 2,500 to 570 million years ago; comprises thePaleoproterozoic ,Mesoproterozoic andNeoproterozoic eras ; marked by the build up ofoxygen in theatmosphere and the emergence of primitivemulticellular life . - proper noun geology The Proterozoic eon.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- noun from 2,500 to 544 million years ago; bacteria and fungi; primitive multicellular organisms
- adjective formed in the later of two divisions of the Precambrian era
Etymologies
from The American Heritage® Dictionary of the English Language, 4th Edition
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Examples
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The assembly and regulatory diversification of the genetic toolkit for animal development undoubtedly underpin Proterozoic and Cambrian evolution …
Continuation… 2008
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Late Proterozoic, so let's say 1,000 to 542.0 million years ago.
Of Books and the Sea greygirlbeast 2010
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Late Proterozoic, so let's say 1,000 to 542.0 million years ago.
Of Books and the Sea greygirlbeast 2010
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Eukaryotic one-celled organisms became dominant in the Proterozoic Eon.
Geologic time 2010
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We parked and spent the afternoon on the rocky beaches, surrounded by high granite cliffs (an unnamed granite formation dating from the Late Proterozoic), searching for bits of beach glass.
"We've been watching you with all our eyes..." greygirlbeast 2008
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In amongst the wildly contorted Proterozoic strata, we spotted small fish, an assortment of hermit crabs (Pagurus spp.), small spider crabs (Libinia spp.), and a number of different taxa of cancroids, including juvenile Rock crabs (Cancer irroratus).
"Here, by the ocean, the sky's filled with leaves..." greygirlbeast 2008
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Knoll and Carroll think there was a mass extinction event at the Proterozoic-Cambrian border.
Continuation… 2008
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This in turn surrounds less common remnants of Proterozoic sediments.
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The fossil record shows that the first eukaryotic life appeared on Earth at the beginning of the Proterozoic aeon, about two gigayears ago, when the Earth was only about half its present age.
George’s Cosmic Treasure Hunt Lucy 2009
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The fossil record shows that the first eukaryotic life appeared on Earth at the beginning of the Proterozoic aeon, about two gigayears ago, when the Earth was only about half its present age.
George’s Cosmic Treasure Hunt Lucy 2009
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