Dental morphology and microstructure of the Prickly DogfishOxynotus bruniensis(Squaliformes: Oxynotidae)

Abstract

This study describes and illustrates the jaws, teeth, and tooth microstructure of the Prickly Dogfish Oxynotus bruniensis. Detailed accounts of the dental morphology of O. bruniensis are rare and have not addressed the tissue arrangement or microstructure of the teeth. These features are documented and discussed in the contexts of interspecific comparisons with other elasmobranchs and the dietary specialization of O. bruniensis. The overall tooth morphology of O. bruniensis is similar to those of other closely related members in the order Squaliformes, as is the tissue arrangement, or histotype. Oxynotus bruniensis exhibits a simplified enameloid microstructure, which we compare with previously documented enameloid microstructures of other elasmobranchs. Though subtle interspecific differences in dental characters are documented, neither overall tooth morphology nor histotype and microstructure are unique to O. bruniensis. We conclude that in the case of O. bruniensis, dietary specialization is facilitated by behavioral rather than morphological specialization.

Shark mandible evolution reveals patterns of trophic and habitat-mediated diversification

“…Taxa in the positive PC2 extreme have a deep symphysis, which is what would be expected of jaws that resist transverse torsional kinesis. These taxa are primarily dalatiid, oxynotid, and somniosid sharks which are characterised by specialised gouging dentitions in which there is only a single row of teeth within the bite, aligned to single blade-like arcade 62 – 64 . Taxa on negative PC2 scores have anteroposteriorly broader dental grooves near the symphysis.…”