It looks fairly small, with very large eyes and some crazy canines for the size. It's hard to tell from the photo, but the eyes appear to be side-facing, not front-facing, which would seem to favor a prey rather than a predator. Rodents generally have large buck teeth, but this skull may have lost those. I'm no expert, though, so I could be way off. As a guess, perhaps a bat? It's hard to judge the size...
Interesting find, though!
It won't let me edit for some reason but I was trying to add that it is small. About the size of a baseball. I thought for a minute it was the beaver I found from a few weeks ago but the skull shape doesn't fit. Bat is a good guess. I'd agree its probably a rodent.
Oh yeah, that's much too big for a bat or a mouse, then, unless it's an ROUS.