The oldest erymnochelyine turtle skull, Ragechelus sahelica n. gen., n. sp., from the Iullemmeden basin, Upper Cretaceous of Africa, and the associated fauna in its geographical and geological context

ABSTRACT We describe the skull of Ragechelus sahelica, n. gen., n. sp., a pleurodiran Pelomedusoides turtle, the oldest skull known of the Erymnochelyinae. The specimen comes from the surroundings of Indamane village, from a littoral late Maastrichtian level of the Iullemeden sedimentary basin (southwestern Niger, Africa). It is compared on the one hand to the members of the subfamily including remains from the neighboring Ibeceten locality, but from an underlying continental Senonian, and, on the other hand, particularly to the bothremydid Nigeremys gigantea (Bergounioux & Crouzel, 1968), from a littoral Maastrichtian level close to that of Indamane, and from a closer to Indamane locality than Ibeceten. The associated fauna is reviewed in its stratigraphic context. Palaeogeographic considerations and systematic relationships indicate Erymnochelyinae widely diversified, in Africa from that time onwards, up to these days in Madagascar and notably with incursions in Western Europe during the Eocene times.