A new itasuchid (Crocodyliformes, Notosuchia) from the Early Cretaceous of Mali and the ancient Paleo-Tegama river system of Gondwana

We describe a new genus and species of notosuchian crocodyliform from the “Continental Intercalaire” of the Republic of Mali represented by cranial, mandibular, and postcranial material. Phylogenetic analysis recovers the new taxon, Sissokosuchus maliensis, within Itasuchidae as the sister taxon to Barreirosuchus, and deeply nested within an otherwise South American radiation. Sissokosuchus is the first itasuchid recognized from the Lower Cretaceous “Continental Intercalaire” of West Africa (with Fortignathus felixi potentially representing a second). Sissokosuchus possesses the apomorphic dentary alveolar couplet morphology present in Itasuchus and other later diverging itasuchids. Our analysis also supports a clade-level dichotomy in rostral morphology: Itasuchidae is dominated by narrower, platyrostral taxa and Peirosauridae by oreinirostral taxa. Sedimentology of the site suggests that Sissokosuchus is associated with a large, ancient fluvial channel system. Paleocurrents and detrital zircon data indicate that sediments were derived from myriad sources to the south and east. Our work corroborates hypotheses indicating westward paleoflow of stratigraphically correlative Aptian–Albian fluvial strata in Niger (that preserve similar taxa) into Mali. We hypothesize that a transcontinental river system, here named the Paleo-Tegama River System, was present during this time draining west out of Niger through Mali and into the Tethys Sea. This paleodrainage system would have acted as a late-lasting inland faunal corridor between South America and West Africa, via the West and Central African Rift System, prior to final Gondwanan break-up, or a post break-up dispersal route via the Tethys, for semiaquatic West African crocodyliforms to reach South America, or vice versa.