Proterozoic

[ prot-er-uh-zoh-ik, proh-ter- ]

noun

the longest geologic eon and the most recent division of Precambrian time, during which the presence of oxygen in Earth’s atmosphere became significant, causing certain life forms to adapt to the use of oxygen and leading to a proliferation of complex multicellular life.

adjective

of or relating to this eon.

Origin of Proterozoic

First recorded in 1905–10; protero- + zo- + -ic

Formerly Algonkian .

Compare Archean.

Words Nearby Proterozoic

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use Proterozoic in a sentence

Proterozoic , the age of invertebrate dominance, containing an early and a late ice age.
Unexplored! | Allen Chaffee
Proterozoic fossils have been found in places where the present average temperature approaches 0°C.
Climatic Changes | Ellsworth Huntington
The recent discovery of glaciation in latitudes as low as 30° in the Proterozoic is correspondingly significant.
Climatic Changes | Ellsworth Huntington
Hence, uplift alone cannot account for extensive glaciation in subtropical latitudes during the Permian and Proterozoic.
Climatic Changes | Ellsworth Huntington
The late Proterozoic or very earliest Cambrian was probably the time of the great splitting up into groups.
The Appendages, Anatomy, and Relationships of Trilobites | Percy Edward Raymond

British Dictionary definitions for Proterozoic

Proterozoic

/ (ˌprəʊtərəʊˈzəʊɪk) /

noun

the later of two divisions of the Precambrian era, during which the earliest plants and animals are assumed to have lived: Compare Archaeozoic

adjective

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

Scientific definitions for Proterozoic

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.

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