Eocene

[ ee-uh-seen ]

adjective

1. noting or pertaining to an epoch of the Tertiary Period, occurring from 55 to 40 million years ago and characterized by the advent of the modern mammalian orders.

noun

1. the Eocene Epoch or Series.

Eocene

/ ˈiːəʊˌsiːn /

adjective

1. of, denoting, or formed in the second epoch of the Tertiary period, which lasted for 20 000 000 years, during which hooved mammals appeared

noun

1. the Eocene
   the Eocene the Eocene epoch or rock series

Eocene

/ ē′ə-sēn′ /

1. The second epoch of the Tertiary Period, from about 58 to 37 million years ago. During the earliest part of this epoch, land connections existed between Antarctica and Australia, between Europe and North America, and between North America and Asia, and the climate was warm. The land connection between Antarctica and Australia disappeared in the mid-Eocene and early Oligocene, resulting in a change in the predominant oceanic currents and a cooler climate. With this change, the average size of mammals changed from less than 10 kg (22 lbs) to more than 10 kg. The Himalayas also formed during the Eocene, and most modern orders of mammals appeared.
2. See Chart at geologic time

Other Words From

• post-Eo·cene adjective

Word History and Origins

Origin of Eocene¹

First recorded in 1825–35; eo- + -cene

Word History and Origins

Origin of Eocene¹

C19: from eo- + -cene

Example Sentences

Those specimens included mammals from 17 groups dating to the Paleocene and 17 to the Eocene, the epoch that spanned 55 million to 34 million years ago.

From Science News

The cathedral’s building blocks are Lutetian limestone, unique to this part of France, formed in a shallow sea during the Eocene period about 45 million years ago.

From Washington Post

The fourth area displays a very different succession of Eocene strata, and one of extreme interest.

From Project Gutenberg

This uplift imprisoned an enormous Eocene lake that occupied much of what is now the Colorado River basin.

From Project Gutenberg

The Middle Eocene is represented by the well-known “Calcaire grossier,” about 90 ft. thick.

From Project Gutenberg

The late Eocene flora of Europe was very similar to its descendant in modern Australasia.

From Project Gutenberg

Marls and limestones with fossils of an Eocene facies overlie the Cretaceous rocks on the Gabun.

From Project Gutenberg