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

• 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