Layman's articles on genetics of skull shape and differences between dog breeds. I'm posting these links now so I can find the official research articles on Monday:
The Genes Behind Fido's Facial Features | Dog Anatomy | LiveScience Genes for Dogs Breeds Discovered | LiveScience
Research article on skull shape:
http://www.plosgenetics.org/article/...l.pgen.1002849
Another article on skull shape:
http://www.genetics.org/content/193/2/317.full