Osteology of the cranium and Weberian apparatus of African catfish families (Teleostei: Ostariophysi: Siluriformes) with an assessment of Palaeogene genera

Abstract

Although the vast majority of fossil catfish material is isolated elements such as fin spines, a number of fossil catfishes (Siluriformes) have been named based on articulated crania from Palaeogene formations of Africa. The fossil taxa from marine sediments have been assigned to the extant marine family Ariidae, or have been assumed to have washed into marine sediments from freshwater habitats. The ability to assess the relationships of these fossils without reference to the nature of the geological sediments may provide insight into the history of these families. Most of the taxonomic work on the 11 catfish families found in Africa has focused on soft-tissues or DNA, which is problematic for the fossil material. Here we provide osteological features to distinguish families of African catfishes; eight of the families that are likely to be found in fossiliferous deposits can be distinguished based on a combination of skull features  including the morphology of the cranial fontanelle, mesethmoid, and dermal ornamentation. We reassess the familial placement of the Palaeogene catfishes. We find that †Eomacrones wilsoni, from the Palaeocene of Nigeria, belongs in Bagridae s.s. This confirms that bagrids were in Africa much earlier than the Miocene. Because this catfish comes from Palaeocene marine sediments, the biogeographic history of Bagridae needs to be reassessed to consider marine dispersal in this taxon.