Challenge: Can you identify this skull?

What creature does this skull belong to? Ask anyone who knows anything about this kind of thing, take a look at these pictures and see if you can make a guess.

I have had it for years in my room, having found it near some rapids in New Zealand, surrounded by fields inhabited primarily by sheep. But this certainly doesn’t look like a sheep skull, and has no visible evidence of ever having a jaw/teeth. Quite large eye sockets, the skull has a strange snout-like thing with a gaping hole in the middle.

I have also sent it off to the Identification forum of the Natural History Museum.