The determinants of postcanine tooth form in omnivorous and dietarily specialized mustelids and viverrids (Mammalia: Carnivora).

摘要

This thesis examined the biological basis for tooth shape differences in closely related species, specifically, the contributions of allometry, functional adaptation, and tooth growth to tooth shape differences in the mustelid and viverrid families. Firstly, a study of dental allometry investigated the relationship between body size and characteristics of the dentition within each family. Secondly, the dentitions of mustelid and viverrid species were studied to determine the extent to which dental form reflected primitive dietary flexibility or specializations for the breakdown of specific foods. The shearing and crushing surfaces of the teeth were compared with predictions of tooth form for maximizing the breakdown of specific foods. Lastly, dental development within the ferret, Mustela putorius, was described through study of serially sectioned tooth primordia and three-dimensional reconstructions of the primordial postcanine teeth at progressive growth stages.;The results of this morphological and ontogenetic study of mustelid and viverrid postcanine dentitions showed that tooth shape results from multiple biological factors. Different allometric equations in each family for tooth size and the extent of shearing and crushing regions determined that different growth trajectories generate tooth form in each family. Thus, evolutionary change in allometric trends resulted in mustelids and viverrids of similar body size that differ greatly in tooth size and the extent of functional surfaces on the teeth. Furthermore, the extent of similarity in tooth form between mustelid and viverrid consumers of a similar diet was associated with the material properties of the dietary components and the extent of dietary specialization. Finally, the ontogenetic trajectories for each ferret tooth crown were observed to be unique and each tooth primordium matured regionally. The combined results of this morphological and ontogenetic study of the postcanine dentition indicated that regions of a tooth crown that develop early are more evolutionarily conservative whereas regions of the dentition that develop late are more variable across taxa.