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.

---

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

---

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

---

Other Word Forms

• post-Miocene
  adjective

Etymology

Origin of Miocene

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

Example Sentences

See Examples For:

Miocene

Masripithecus shows that apes were already living in North Africa during the Early Miocene.

From Science Daily ● Jul. 24, 2026

Before this discovery, Early Miocene fossil sites in North Africa had produced remains of monkeys but no confirmed apes.

From Science Daily ● Jul. 24, 2026

During the Miocene, the area experienced warm and wet rainforest conditions.

From Science Daily ● Apr. 23, 2026

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

From Science Daily ● Mar. 27, 2026

I told him I was studying hard because I wanted to become either a veterinarian or a geologist specializing in the Miocene period, when the mountains out west were formed.

From "The Glass Castle" by Jeannette Walls