Paleoparadoxia is a genus of large, herbivorous aquatic mammals that inhabited the northern Pacific coastal region during the Miocene epoch. It ranged from the waters of Japan, to Alaska in the north, and down to Baja California, Mexico.

The Desmostylia are an extinct order of aquatic mammals native to the North Pacific from the early Oligocene (Rupelian) to the late Miocene (Tortonian). Desmostylians are the only known extinct order of marine mammals.