A VERTEBRATE FAUNA FROM THE LOWER CARBONIFEROUS OF KENTUCKY DOMINATED BY LARGE CHONDRICHTHYANS

A horizon within the Salem Formation of Hardin County, Kentucky was investigated for vertebrate remains and found to contain examples of teeth and tooth plates from Ctenacanthiform (Saivodus striatus), Petalodontifom (Antilodus sp., Polyrhizodus concavus, and Chomatodus sp.), and Cochliodontiform (Deltodus sp.) chondrichthyans that are larger than what are typically reported from other fossil localities. The teeth of the Psammodontiform cf. Lagarodus are also atypically common from this location when compared to other occurrences of marine vertebrate faunas from the Carboniferous. Overall, the biodiversity among chondrichthyan remains that are somewhat larger than expected could suggest that these animals made dietary use of an energy source that was not utilizable in other lower Carboniferous reef ecosystems. It is not clear, however, what this food item could have been since Petalodonts are often interpreted as predators or durophagous, cochliodonts could only be durophagous, and S. striatus was probably an apex predator that specialized on other vertebrates. Additionally the cf. Lagarodus specimens reported here are generally older than other examples and lack a key diagnostic feature of the type species, which implies that cf. Lagarodus fossils here may represent an unknown but primitive psammodontiform species.