Developmental transition to monophyodonty in adaptation to marine life by the northern fur seal, Callorhinus ursinus (otariidae)

Abstract

The foetus of the northern fur seal has a rudimentary deciduous dentition that is shed into the amniotic fluid at a late stage of pregnancy. At birth, the pup possesses a well developed permanent dentition. Normally, the first postcanine is monophyodont, its deciduous predecessor having been eliminated from the pattern of development. In rare cases, an atavistic first postcanine is present on one side of the jaw. These observations document the evolutionary transition from a diphyodont to a monophyodont condition in the development of the masticatory system of the northern fur seal. Fur seal pups acquire their permanent dentitions at an early developmental stage so as to be able to hunt independently even prior to being weaned.

Keywords:

• Fur seal
• Callorhinus
• Dentition
• Deciduous teeth
• Polymorphism
• Atavism
• Asymmetry
• Development
• Adaptation
• Aquatic life

Notes

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