A revision of the Upper Cretaceous lepidosirenid lungfishes from the Quseir Formation, Western Desert, central Egypt

We evaluate new lungfish remains from the Upper Cretaceous Quseir Formation in the Western Dessert of southern Egypt. Taxa include Lavocatodus protopteroides, L. humei, L. giganteus, and Protopterus nigeriensis. We treat Lavocatodus as members of Lepidosirenidae based on the presence of a well-defined medial articular surface, in the absence of a symphyseal surface of corresponding prearticular bones. Material of L. protopteroides represents the first example of an adult specimen, supporting the retention of the species as valid, and not a junior synonym of L. humei. Specimens of L. humei are the most abundant in the assemblage, and all exhibit the medial articular surface, a feature that is absent from specimens of Ceratodus; therefore, we reassign additional specimens of ‘C.’ humei to Lavocatodus. New specimens of L. giganteus extend the temporal and spatial ranges of the species (the type material of L. giganteus is from Paleocene deposits of In Farghas, Mali). Finally, a new specimen of Protopterus represents the oldest record of the genus in Egypt. The prearticular is confidently assigned to Protopterus based on the presence of only three ridges on the tooth plate, a medial symphyseal suture, a coronoid process, and a shallow tooth crown plus prearticular depth. We further assign it to P. nigeriensis based the length and merger of tooth ridges. Furthermore, the oldest Cenomanian specimens reported from the Sudan Wadi Milk Formation are assigned to P. nigeriensis, which would extend the temporal range of P. nigeriensis by roughly 14 Ma.