I googled a muskrat and this is what it said of its teeth:

....Only a minimal amount of hair grows on the feet. The hand-like front feet are used in building lodges, holding food, and digging burrows and channels. Although the larger hind feet are used in swimming, they are not webbed like those of the beaver and otter. Instead, the four long toes of each foot have a fringe of specialized hairs along each side, giving the foot a paddle-like effect. The rather small ears are usually completely hidden by the long fur. The four chisel-like front teeth (two upper and two lower incisors), each up to 2cm long, are used in cutting stems and roots of plants.

These two top teeth (incisors) are almost 2 inches long. This must have been a large muskrat, or one with above normal teeth. It has 3 molars on each side of top jaw that look like they were made for chewing vegitation. Whatever it is...or was is a unique display of Gods creatures and their adaption to chewing, or in this case devouring its food.

Thanks for the input everyone. Im kinda a collector of skulls I find while I am scouting, and this one is very unique to say the least!