Neotherium mirum is an extinct species of basal walrus.Berta, Annalisa. 2002b. "Pinniped Evolution". In Encyclopedia of Marine Mammals, eds. Perrin, William F., Bernd Würsig, and J. G. M. Thewissen. Academic Press. It was smaller than living forms and it did not have long tusks. Males were larger than females.
Palaeoecology Stable isotope evidence indicates that in the eastern North Pacific, Neotherium had intermediate foraging habits between the nearshore specialist Pithanotaria and the offshore specialist Allodesmus.
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