A new crossognathiform fish (Actinopterygii, Teleostei) from the Upper Cretaceous (Turonian) of southern Morocco with hypertrophied fins

A new genus and species of basal teleost, Kradimus asflaensis gen. et sp. nov., is described from the Cenomanian–lower Turonian Akrabou Formation of Morocco. Uniquely, it possesses greatly hypertrophied pectoral and dorsal fins, with the pectoral fins longer than the body. Morphological similarities with Crossognathiformes, particularly the pachyrhizodontoid Notelops, suggest crossognathiform and possibly pachyrhizodontoid affinities. A phylogenetic analysis demonstrates that its placement within Crossognathiformes is uncertain. Therefore, we assign the taxon as a crossognathiform incertae sedis. We also explore possible functions of the hypertrophied pectoral and dorsal fins. Based upon comparisons with fish with similar fin morphologies, gliding fish (Exocoetidae, Thoracopteridae) and fast-swimming fish (Istiophoridae, Scombridae, Xiphiidae), we find that the pectoral and dorsal fins are unlikely to have served a primary locomotory function. Instead, we suppose that they functioned in an unknown form of display. Further study and collection of fossil material is required to satisfy both the taxonomic placement of Kradimus asflaensis gen. et sp. nov. and the function of its highly unusual fins.