Palaeocene (Palaeo|cene)

adjective

• relating to or denoting the earliest epoch of the Tertiary period, between the Cretaceous period and the Eocene epoch.
• (as noun the Palaeocene) the Palaeocene epoch or the system of rocks deposited during it.

• The Paleocene epoch lasted from 65.0 to 56.5 million years ago. It was a time of sudden diversification among the mammals, probably as a result of the mass extinctions (notably of the dinosaurs) which occurred at the end of the Cretaceous period (see Cretaceous-Tertiary boundary)