Oligocene
Americanadjective
noun
adjective
noun
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The third epoch of the Tertiary Period, from about 37 to 24 million years ago. During this time there was an increase in volcanic activity, and Australia and South America separated from Antarctica. The climate started to cool and a glacier started to form in Antarctica. Modern mammalian groups continued to develop, and the first cats, dogs, horses, and related mammals appeared. Artiodactyls (even-toed ungulates) took over from the perissodactyls (uneven-toed ungulates) as the dominant medium-sized herbivores. Many types of grass also first appeared at this time.
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See Chart at geologic time
Other Word Forms
Etymology
Origin of Oligocene
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
The Gibraltar arc formed in the Oligocene as a part of the Western Mediterranean subduction zones.
From Science Daily ● Feb. 15, 2024
"However, given their importance, most of these have yet to be properly described, and our understanding of species richness and relationships between Oligocene odontocetes from the North Pacific is not fully understood," the authors write.
From Salon ● Jun. 24, 2023
Based on the location and age of the rocks surrounding the ant hills, the researchers estimate that the fossils are from the late Eocene and early Oligocene epochs.
From New York Times ● Jul. 1, 2022
This other Wakaleo species is just about as old, going back to the Late Oligocene, and points to an even earlier origin for the group.
From Scientific American ● Dec. 16, 2017
We pass on to strata which used to be called Upper Eocene, but are now generally classified as a period by themselves, and called the Oligocene.
From The Geological Story of the Isle of Wight by J. Cecil Hughes
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
