Looks like a dog, with the nose and turbinate structures behind it missing.
The thinner flesh around the mouth is missing, exposing the lower and upper jaw bones.
I found a dog skeleton in the desert near Holser Canyon (Where Steel Challenge is), and the entire “nose structure” was missing from the Jacobsens’ Organ pits up almost to between the orbits, though the rest of the skull looked intact. Sort of similar, but mine had been baked in the sun, rather than soaked in salt water.
I agree it looks like any number of mammalian skulls with the soft nose tissue missing. But what about the upper teeth? The only things I can think of with no upper teeth are most ruminants. And those, I can’t think of one that has lower canines.
I can think of a few that have long upper canines such as musk deer and chinese water deer.