Of, belonging to, or designating the geologic time, rock series, and sedimentary deposits of the first epoch of the Tertiary Period, preceding the Eocene Epoch and characterized by the appearance of placental mammals.

• 古新代的属于或是地质时代、岩系的段和沉积矿床第三纪的第一时代的，早于始新世时代并且以胎生哺乳动物的出现为特征