Dog skulls vs. wild canids

Fig. 3 from Robert K. Wayne (1986) "Cranial Morphology of Domestic and Wild Canids: The Influence of Development on Morphological Change," Evolution, 40(2):243-261. It shows an analysis of skull measurements from several species of domestic dogs (dots), other members of the genus Canis (labeled 1), fox-sized species (labeled 2-5), other species (labeled 6), and Canis lupus, the grey wolf (labeled 1a).