Aulophyseter is a genus of predatory whale that lived in North America during the Miocene epoch. It was similar to a modern day Sperm Whale, but had a more diverse diet. Compared to other primitive whales, Aulophyseter had more and smaller teeth and therefore, probably, hunted on fish and maybe squid. It hunted by echolocation using the melon on its head.
Aulophyseter morricei is known from several fossils found in the Shark Tooth Hill formation in California (USA). The genus has been found on both sides of the USA and it is therefore possible Aulophyseter migrated through the Central American Seaway. When the sea levels dropped at the end of the Miocene epoch, the landbridge between North and South America appeared and blocked the path for these whales. It is known that this event caused the death of many species of prehistoric whale.
Kellogg, R. (1927). Study of the skull of a fossil sperm-whale from the Temblor Miocene of southern California. Carnegie Institution of Washington.