Named By: Douglas Emlong - 1966.
Classification: Chordata, Mammalia, Cetacea, Mysticeti, Aetiocetidae.
Species: A. cotylalveus (type), A. polydentatus, A. tomitai, A. weltoni.
Type: Carnivore/Filter Feeder.
Size: Approximately 7.5 meters long.
Known locations: USA, Oregon - Yaquina Formation.
Time period: Oligocene of the Palaeogene.
Fossil representation: Almost complete skulls and partial post cranial remains, identifying four species so far.
Aetiocetus is an important transitional form as it displays the early origins of the baleen whales, while still retaining teeth that can be identified as incisors, canines and molars like many other mammals. Later descendants would go on to become exclusive filter feeders like many of the modern great whales that swim our oceans today.