Originally found throughout the northern hemisphere, with many local varieties. Wolves are interfertile with coyotes and domestic dogs. It is difficult to specify characteristics which separate wolf from domestic dog skulls, due to the great diversity of size and shape in dogs, and the fact that all domestic dogs are descended from wolves. One of the consistent effects of domestication in this species seems to be a deterioration in the quality of the teeth.

Wolf Skull, lateral view
 
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Internet Resources

MS : UM (explained)

References

Linnel et al 2002 - Review of wolf attacks