This new specimen consist in a partial skull, still has to be formally described, being somewhat larger and older than A.deinodon. Acrophyseter robustus is thought to be a powerful biter as exostoses in its jaws indicates great forces when biting like modern False Killer whale
Has been years since that publication and certainly unpublished material, primarily teeth of stem-physeteroids have been found as lower as the earliest Pliocene, a form of Acrophyseter may had coexist with all these genera at AGL. Acrophyseter seems to be a really succesful genus back then.
Ah so, Acrophyseter appears in the Pliocene...so it's Livyatan and its fauna, a small gap at the end of the Miocene and finally Acrophyseter appears? The SSW part is dated at a little over 6-5 mya anyway, that's end Miocene. I saw the new paper about the re-dating of the Pisco physeteroids and the re-dating of Livyatan to about 9 mya in Pisco, Cerro del Brugos I think it was called? I don't remember. Anyway the dating and fauna for Sud-Sacao West, is it still good?
Yes, from Cerro La Bruja, in terms of time, A.robustus may have coexisted with Livyatan, then we have this Acrophyseter sp and later A.deinodon, there is also undescribed material, teeth of what may be a even larger species from the earliest Pliocene. Yes the dating is still good.
Oh, so there really aren't any at Sud-Sacao West? I'm rather confused now, since SSW is latest Miocene...how odd then, actually. Four species of Acrophyseter throughout the Pisco Formation is incredible.
One thing I always wonder about prehistoric whales is the shape of their head, especially with animals that look like this: how do we know it had such a head?
Well thats somewhat hard to tell since soft tissue havent preserved, however the shape of the skull gives a hint of how the cetaceans would have look like, in this case the shape of the skull indicates that acrophyseter spermaceti organ didnt extended forward to the tip of the snout as physeter. How we know this? the snout isnt concave as in Physeter so lt probably had a profile similar to a delphinoid or beaked whale.