Desmostylians

Desmostylia (from Ancient Greek δεσμά (desmá), meaning "bundle", and στῦλος (stûlos), meaning "pillar") is 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. Their taxonomic placement within Placentalia is subject to considerable debate.

Desmostylus is an extinct genus of herbivorous mammal of the family Desmostylidae living from the Chattian stage of the Late Oligocene subepoch through the Late Miocene subepoch (28.4 mya–7.250 Mya) and in existence for approximately .

Paleoparadoxia ("ancient paradox") 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 (Tsuyama and Yanagawa), to Alaska in the north, and down to Baja California, Mexico.

Behemotops (from the Biblical monster Behemoth, by Linnaeus and others believed to be a hippo) is an extinct genus of herbivorous marine mammal. It lived from the Early Oligocene (Rupelian) through the Late Oligocene (33.9 mya—23 Mya), existing for approximately . It is the most primitive known desmostylian, believed to be close to the ancestry of all other desmostylians.

Desmostylidae is an extinct family of herbivorous marine mammals belonging to the order of Desmostylia. They lived in the coastal waters of the northern Pacific Ocean from the Early Oligocene (Rupelian) through the Late Miocene (Tortonian) (33.9 mya—7.2 MYA), existing for approximately .

thumb|left|Life reconstruction of a young Neoparadoxia.Neoparadoxia is an extinct genus of large, herbivorous aquatic desmostylian mammals from the Miocene Ladera and Monterey Formations of North America.The name comes from the Latin "Neo", meaning new, and Paleoparadoxia, a related genus of desmostylian.

Cornwallius is an extinct herbivorous marine mammal of the family Desmostylidae. Cornwallius lived along the North American Pacific Coast from the Early Oligocene (Chattian) into the Early Miocene (28.4 mya—20.6 Mya) and existing for approximately .