Paleoparadoxia ("ancient paradox") is a genus of large, herbivorous aquatic mammals that inhabited the northern Pacific coastal region during the Miocene epoch (20 to 10 million years ago). It ranged from the waters of Japan (Tsuyama and Yanagawa), to Alaska in the north, and down to Baja California, Mexico. Paleoparadoxia was about 2.2 m (7 ft 3 in) long.