Definitions for paleoceneˈpeɪ li əˌsin; esp. Brit. ˈpæl i-
Random House Webster's College Dictionary
Pa•le•o•ceneˈpeɪ li əˌsin; esp. Brit. ˈpæl i-(adj.)
noting or pertaining to an epoch of the Tertiary Period, from 65 million to 55 million years ago, a time of mammalian proliferation.
(n.)the Paleocene Epoch or Series.
Origin of Paleocene:
Paleocene, Paleocene epoch(noun)
from 63 million to 58 million years ago; appearance of birds and earliest mammals
The Paleocene epoch.
Of or pertaining to a geologic epoch within the Paleogene period from about 65 to 56 million years ago; marked by the rise of the first large mammals in a tropical climate.
The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about 66 to 56 million years ago. It is the first epoch of the Palaeogene Period in the modern Cenozoic Era. As with most other older geologic periods, the strata that define the epoch's beginning and end are well identified but the exact date of the end is uncertain. The Paleocene Epoch immediately followed the mass extinction event at the end of the Cretaceous, known as the Cretaceous–Paleogene boundary, which marks the demise of non-avian dinosaurs, the giant marine reptiles and much other fauna and flora. The die-off of the dinosaurs left unfilled ecological niches worldwide. The name "Paleocene" comes from Greek and refers to the "old" "new" fauna that arose during the epoch.