Dentition of the Northern Elephant Seal

The milk and permanent dentitions from 61 northern elephant seals (Mirounga angustirostris) were analyzed to reveal tooth morphology, postcanine formulae, and eruption sequence of the permanent teeth. By studying large numbers of pups, morphology of the milk teeth was elucidated and three morphological types of permanent postcanines were distinguished. The first permanent lower premolar is frequently deleted, corresponding to exaggerated permanent canine development. Asymmetry in the permanent postcanine formula is common (63 per cent of individuals exhibit asymmetry) with the most frequent anomalies being deletion of lower premolar 1 and presence of a second molar in the lower jaw. There are suggestions that the dentition of northern elephant seals (M.angustirostris) differs from that of southern elephant seals (M.leonina) in several aspects, including frequencies of occurrences of the first upper molar and lower premolar 1, eruption sequence of permanent teeth, and degree of confluence of the alveoli of fourth premolars and first molars.