Studies in functional and analytical graniology. 4. More extreme forms of the Breviarcuate skull.

Abstract

The breviarcuate character of the dog's skull is not very pronounced. More advanced adaptations among the carnivorous mammals towards the full development of the breviarcuate skull are described and analysed in detail. When we compare the transformations in the zygomatic arch region of more strongly breviarcuate skulls with that in the skull of Canidae, it is clear that they are bound up with the muscular differences and involve: the lesser distance between the canines and the zygomatic arch; the greater strength of fronto-zygomatic connections; the larger surfaces connecting the malar bone and maxilla; the fact that the zygomatic arch is not divided at its connection with maxilla; the development of the lamellar system and the presence of the gomphus (a non-mobile joint in which one bone fits into a groove or cavity in the other) in the maxillo-malar junction. The detailed structure of these connections is described. Also described is a shallow depression on the malar bone in which lies the end of the zygomatic process of the squamosal bone, with its function and connections. Most of the analyses are based on the skull of the domestic cat.