Name: Acrophyseter ‭(‬Acute sperm whale‭)‬.
Phonetic: Ack-roe-fie-set-er.
Named By: Lambert,‭ ‬Bianucci‭ & ‬Muizon‭ ‬-‭ ‬2008.‭
Classification: Chordata,‭ ‬Mammalia,‭ ‬Cetacea,‭ ‬Physeteroidea.
Species: A.‭ ‬deinodon‭ (‬type‭), A. robustus.
Diet: Carnivore.
Size: Estimated at‭ ‬4‭ ‬meters long.
Known locations: Peru.
Time period: Messinian of the Miocene.
Fossil representation: Partial skull and mandible‭ (‬lower jaw‭)‬.

       When you translate the full name of Acrophyseter deinodon into English you end‭ ‬up with‭ '‬acute sperm whale terrible teeth‭'‬.‭ ‬The genus part of‭ '‬acute sperm whale‭' ‬is a reference to the upturned bend in the jaws,‭ ‬suggesting that Acrophyseter may have approached prey from below.‭ ‬The species name deinodon,‭ ‬or‭ '‬terrible teeth‭' ‬is a reflection of the large and strong conical teeth that were in both jaws.‭ ‬The front teeth are angled to point forwards,‭ ‬probably an adaptation to facilitate prey capture.‭ ‬From here prey was probably passed to the tightly packed back teeth of the lower jaw that were better suited to shearing through flesh.
       Acrophyseter was probably a generalist hunter,‭ ‬whose prey included other marine mammals including other smaller whales,‭ ‬fish,‭ ‬and maybe even birds like penguins.‭ ‬Smaller prey could have been killed almost instantly,‭ ‬but larger prey like whales may have had to have been worn down,‭ ‬perhaps by concentrating attacks on areas like the tail fluke to immobilise the prey.‭ ‬The jaws and teeth of Acrophyseter seem to have been well suited for this purpose as the front teeth would have easily been able to grip a tail fluke in motion with the rear teeth easily being able to cut through it.‭ ‬It is unknown if Acrophyseter hunted in pods like Orca‭ (‬also known as killer whales‭) ‬do today.‭ ‬However study of small cetaceans does indicate a strong possibility that Acrophyseter may have hunted in family pods to coordinate efforts upon prey.
       Acrophyseter has been placed in the Physeteroidea which includes other predatory whales such as Brygmophyseter,‭ ‬Zygophyseter,‭ ‬Aulophyseter and the huge Livyatan.

Further reading
- A new stem-sperm whale (Cetacea, Odontoceti, Physeteroidea) from the Latest Miocene of Peru. Comptes Rendus Palevol 7(6):361-369 - O. Lambert, G. Bianucci & C. Muizon - 2008.


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