Variations in dental formula of Otaria byronia Blainville (Pinnipedia, Otariidae) from Pacific: A new kind of anomaly
DOI:
https://doi.org/10.4013/5109Abstract
Fourteen South American sea lion specimens from the Pacific population (Chile and Peru) containing dental anomalies are presented from a total sample of 296 specimens. Postcanine agenesis, especially in the upper PC6, is the most frequent anomaly related to the natural instability of this tooth in this species. Although its occurrence is treated as a taxic atavism, we speculate that its presence in other otariid species may be regarded as a vestigial or rudimentary structure. Lower post-canine extra teeth at the PC6 position, corroborates the spontaneous atavism hypothesis back in time to the beginning of the Pinnipedimorpha evolution at Oligo/Miocene. The first case of multiple agenesis for Otaria byronia is here presented. The upper PC2 and PC3 and the lower PC4 are absent on both sides characterizing an oligodonty, a dental anomaly common in other mammal species, such as dogs and humans. The study of dental anomalies can furnish important amounts of information concerning dental evolution of Pinnipedia and contribute to the elucidation of their phylogenetic relationships among the Carnivora Arctoidea.
Key words: agenesis, atavisms, supernumeraries, oligodonty.Downloads
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