The histology of Middle Devonian chondrichthyan teeth from southern Victoria Land, Antarctica

WA Museum Records and Supplements | Updated 1 decade ago

Abstract - The tooth histology of recently discovered Middle Devonian (Givetian) elasmobranchs Antarctilamna prisca, Aztecodus harmsenae, and Portalodus bradshawae has been investigated using fluorescence and scanning electron microscopy. The internal structures of the crowns are surprisingly different in these three Antarctic genera. Only Portalodus has an enameloid cap overlying orthodentine and a core of trabecular dentine. Antarctilamna's crown is constructed of ortho- and trabecular dentine, whereas Aztecodus only shows pleromin.

A cladistic analysis based on the hard tissues reveals that Antarctilamna may be the sister group of the specialized and successful xenacanthid sharks. The relationships of other Palaeozoic elasmobranchs remain unresolved.