Fishes and palaeogeography of the African drainage basins: Relationships between Chad and neighbouring basins throughout the Mio-Pliocene

The Neogene African fossil record of two fishes, i.e. Semlikiichthys (Perciformes indet.) and Calarius (Siluriformes, Ariidae) is reviewed including new material from Chadian outcrops. Their distribution confirms the existence of a Nilo-Sudan ichthyological province. During an early part of the Miocene an east–west waterway is demonstrated to have crossed Africa. Allopatric speciation in the Chadian and East African areas suggests that a split occurred in this system prior to 7 Ma. Moreover, our data support the existence of hydrographical connections between the Chadian basin and the Syrte basin, after 7 Ma, at about the Mio-Pliocene boundary. Finally, our study also demonstrates that connections between the Niger and Chad basins existed at the very end of the Miocene.