A new pipid from the Cretaceous of Africa (In Becetèn, Niger) and early evolution of the Pipidae

Pipimorpha and its crown-group Pipidae possess one of the most extensive fossil records among anurans, known since the Early Cretaceous in both Laurasia and Gondwana. Pipimorph diversification may have been driven by the breakup of West Gondwana during the Cretaceous. Numerous fossils from South America have been unearthed in the last decade, documenting this event. Unfortunately, Cretaceous pipimorphs from Africa have been limited to a few wellpreserved taxa from sub-Saharan Africa and the Arabian Peninsula, which hinders our comprehension of pipimorph diversification during this key period. The site of In Becetèn, in south-east Niger, is one of the few mid-Late Cretaceous (Coniacian–Santonian) sites from which a pipid, Pachycentrata taqueti, is known. Here, we describe and name a second pipid from the same locality. This taxon is known by a relatively complete braincase. Phylogenetic analyses confirm its position as a pipid, with pipinomorph affinities. This makes In Becetèn the oldest site with at least two pipids. Phylogenetic results are congruent with recent pipimorph relationships, with the presence of an endemic extinct clade in South America, Shelaniinae. The phylogenetic results also allow us to review the proposed definition for Pipimorpha and its subclades and propose new systematic definitions for them. Temporal calibration of the phylogenetic tree based on the fossil record suggests that pipimorphs diversified in a western Gondwana block and confirms that South America separated from Africa around the mid-Cretaceous. Between these two events, pipids diverged in Africa, giving rise to major extant clades. This study highlights the importance of Africa for early pipid diversification during the Cretaceous and of the opening of the Southern Atlantic Ocean for anuran dispersion and diversification.