Dental morphology of pycnodont fish vomerine teeth from the Late Jurassic of Poland and its impact on feeding ecology in durophagous osteichthyans

Abstract

This study describes the detailed analysis of an exceptionally well-preserved specimen of pycnodont fish vomerine teeth from the Upper Jurassic limestones of the Owadów-Brzezinki Quarry Lagerstätte in central Poland (Tomaszów Mazowiecki area). X-ray microtomography (µ-CT) revealed the details of the pycnodont tooth morphology and histology. Using the non-destructive technique of X-ray microtomography for exploring the internal structure of fossil teeth in 3D, we were able to recognize individual skeletal tissues. Petrodentine (a specific hypermineralized type of dentine) is present in the pycnodont teeth. This skeletal tissue is common in durophagous vertebrates. The presence of petrodentine in the specimen investigated is interpreted by comparison with extinct and extant dipnoans, which are also durophagous fish and are among the closest ecological analogues of pycnodonts. Microtomography revealed unexpected patterns in the internal architecture and tissue density of the upper jaw. Specifically, the posterior region of the vomer displays higher bone density and significantly larger, more heavily mineralized teeth compared to the anterior portion. These findings suggest a greater biomechanical resistance of the posterior upper jaw to crushing forces. The material described supplements knowledge of Late Jurassic ichthyofaunas and ecosystems in the central and eastern parts of the European Archipelago.