Acta Musei Moraviae

Oxfordian pliosaurids of the northern Tethys within the context of the thalassophonean phylogeny

Apparent differences between the faunal compositions of Callovian (late Middle Jurassic) and Kimmeridgian–Tithonian (middle to late Late Jurassic) marine diapsids of Europe suggest that a faunal turnover occurred during the Oxfordian (early Late Jurassic). The differences in the structures of marine diapsids are usually discussed within the context of the sub-Boreal realm. However, the knowledge of fossil faunas from the Oxfordian of adjacent areas that at least shortly communicated with the northern European marine ecosystems, such as the northern Tethyan realm, is crucial for inferences of diapsid migration patterns and faunal replacements in general. Here we provide an initial insight into the marine diapsids of northern Tethyan areas. Specifically, we describe two incomplete specimens of pliosaurid tooth crowns from the middle or upper Oxfordian of Stránská skála, Czech Republic, comment on their biostratigraphic and paleoenvironmental settings, and compare them to the crowns of other Middle and Late Jurassic pliosaurid taxa. The morphology of the specimens, including the subcircular cross-sectional shapes, and the appearance and distribution of the apicobasal ridges resemble the tooth crowns of the Callovian thalassophonean Liopleurodon ferox. Nevertheless, due to the fragmentary nature of the finds, unambiguous attribution to the macropredatory taxon is impossible. Still, the material supplements our knowledge of the paleobiogeographic distribution of the early Late Jurassic thalassophonean pliosaurids.