Eocene adjective & noun. ['i:ǝ(ʊ)si:n] M19.
[from EO- + Greek kainos new, recent.]
Geology.
A. adjective. Designating or pertaining to the second epoch of the Tertiary period or sub-era, following the Palaeocene and preceding the Oligocene, or (formerly) this together with the Palaeocene and Oligocene. M19.
b. noun. The Eocene epoch; the series of rocks dating from this time, bearing evidence of an abundance of mammals, including early forms of horses, bats, and whales. M19.

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