n. 始新世, 始新系

a. 始新世的, 始新系的

[ noun ]
from 58 million to 40 million years ago; presence of modern mammals
<noun.time>

Eocene \E"o*cene\, a. [Gr. 'hw`s 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.