I originally was tempted to say badger too,
But most of the skulls I've seen have a fin-like blade running behind the brain cavity to anchor the jaw muscles - so I was erring toward young rather than old - along with the general size of it compared to the keys........
It was spotted last september, so I'm not sure how large the previous years young would be, accounting for death to decay etc.
Looks a little alien-esque though doesn't it?
Ogri the trog