資料來源 : pyDict

始新世,第三紀下層始新世的,第三紀下層的

資料來源 : Webster's Revised Unabridged Dictionary (1913)

Eocene \E"o*cene\, a. [Gr. ? daybreak, dawn + ? new, recent.]
   (Geol.)
   Pertaining to the first in time of the three subdivisions
   into which the Tertiary formation is divided by geologists,
   and alluding to the approximation in its life to that of the
   present era; as, Eocene deposits. -- n. The Eocene formation.
   --Lyell.

資料來源 : WordNet®

Eocene
     n : from 58 million to 40 million years ago; presence of modern
         mammals [syn: {Eocene epoch}]