Miocene

American  

[mahy-uh-seen] / ˈmaɪ əˌsin /

adjective

1. noting or pertaining to an epoch of the Tertiary Period, occurring from 25 to 10 million years ago, when grazing mammals became widespread.

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noun

1. the Miocene Epoch or Series.

Miocene British  

/ ˈmaɪəˌsiːn /

adjective

1. of, denoting, or formed in the fourth epoch of the Tertiary period, between the Oligocene and Pliocene epochs, which lasted for 19 million years

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noun

1. this epoch or rock series

Miocene Scientific  

/ mī′ə-sēn′ /

1. The fourth epoch of the Tertiary Period, from about 24 to 5 million years ago. During this time the climate was warmer than it had been in the Oligocene, and kelp forests and grasslands first developed. With the isolation of Antarctica, a circumpolar ocean current was established in the southern Hemisphere, reducing the amount of mixing of cold polar water and warm equatorial water and causing a buildup of ice sheets in Antarctica. The African-Arabian plate became connected to Asia, closing the seaway which had previously separated Africa from Asia. Mammalian diversity was at its peak.

2. See Chart at geologic time

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Other Word Forms

• post-Miocene adjective

Etymology

Origin of Miocene

First recorded in 1825–35; mio- (from Greek meíōn “less”) + -cene

Example Sentences

These early apes later spread into Eurasia between about 14 and 16 million years ago during the Miocene.

From Science Daily • Mar. 27, 2026

However, the new analysis indicates that these movements may have continued much later, possibly into the Miocene.

From Science Daily • Mar. 24, 2026

The Tatacoa Desert is home to rich deposits of fossils from an epoch known as the Middle Miocene.

From BBC • Jul. 22, 2025

For prehistory fans, the Miocene, with its fantastic mammal life, is an immensely attractive period.

From Salon • Feb. 17, 2025

My favorite rocks to find were geodes, which Monyaid came from the volcanoes that had erupted to form the Tuscarora Mountains millions of years ago, during the Miocene period.

From "The Glass Castle" by Jeannette Walls