[ pey-lee-uh-seen or, esp. British, pal-ee- ]
/ ˈpeɪ li əˌsin or, esp. British, ˈpæl i- /


noting or pertaining to an epoch of the Tertiary Period, from 65 to 55 million years ago, and characterized by a proliferation of mammals.


the Paleocene Epoch or Series.

Origin of Paleocene

First recorded in 1875–80; paleo- + -cene Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020

Examples from the Web for paleocene

Scientific definitions for paleocene

[ pālē-ə-sēn′ ]

The earliest epoch of the Tertiary Period, from about 65 to 58 million years ago. During this time, the Rocky Mountains formed and sea levels dropped, exposing dry land in North America, Australia, and Africa. Many new types of small mammals evolved and filled the niches left empty after the extinctions that ended the Cretaceous Period. Soft-bodied squid replaced the ammonites as the dominant form of mollusk. See Chart at geologic time.
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