Dental anomalies in pinnipeds (Carnivora: Otariidae and Phocidae): occurrence and evolutionary implications

摘要

Dental anomalies comprise variations in number, shape, size, position and occlusion of teeth, mainly caused by genetic mechanisms. This study aimed to investigate the nature and prevalence of dental anomalies in a large sample of pinnipeds (Otariidae and Phocidae) and to discuss potential evolutionary and ecological implications. Thirty-four species in twenty genera were sampled. The dentition of the specimens examined was compared with the normal dental formula for the species, and supernumerary and congenitally missing teeth were identified and recorded. Agenesis was observed in 0.93 % of the specimens analyzed (n = 10), being more frequent in otariids. The posteriormost upper postcanines were the teeth absent most frequently. Supernumerary teeth were observed in 1.8 % of the specimens (n = 19), more commonly in phocids. Supernumerary teeth can be interpreted as either atavistic manifestations (particularly for the posteriormost postcanines in Otariidae) or cases of disturbances in dental morphogenesis leading to the formation of extra teeth when they occur in other positions of the tooth row. Morphological dental variants such as ectopic and geminated teeth were also recorded. Cases of dental anomalies should have a limited effect on the functional morphology of the feeding apparatus in pinnipeds, with little influence on the fitness and performance of the animals. Nevertheless, understanding patterns of dental variation should contribute to future studies aiming to elucidate aspects of dental evolution and the phylogenetic relationships of pinnipeds.