Answer: paleocene

AnswerCrossword Clue
PALEOCENEOf a Tertiary epoch
paleocenebelonging to a certain geological time period also PALEOGENE
paleoceneOf, relating to, or denoting the earliest epoch of the Tertiary period, between the Cretaceous period and the Eocene epoch
paleoceneThe Paleocene epoch or the system of rocks deposited during it