Desmostylia




Desmostylia (from Greek δεσμά desma, "bundle", and στῦλος stylos, "pillar") is an extinct order of aquatic mammals that existed from the late Oligocene (Arikareean) to the late Miocene (Tortonian) (30.8 to 7.25 million years ago).
Desmostylians are the only known extinct order of marine mammals.