Functional and phylogenetic significance of integrated growth and form in occluding monkey canine teeth (Alouatta caraya and Macaca mulatta)

Crown-root lengths in paired apposing, functionally interacting monkey canine teeth (Alouatta caraya and Macaca mulatta) are highly correlated throughout their concurrent development. Regression is rectilinear and growth pattern accretional. The differential growth rate is not significantly different in the sexes within each species during concurrent tooth pair development. These integrated morphological characteristics are adaptations to functional needs imposed by jaw anatomy and masticatory dynamics. Divergence from rectilinearity occurs in the mature male Macaca mulatta with the continued growth of the maxillary canine fang after cessation of growth of the apposing mandibular canine tooth. This altered tooth pair crown-root length relationship is associated with the subordination of mastication in these predominantly piercing and slashing teeth. Species differences in regression are significant and afford insight into possible preadaptive factors determining divergent paths in the evolution of canine tooth sexual dimorphism.