New data on Araripesuchus wegneri (mesoeucrocodylia, notosuchia)

The small-sized Araripesuchus wegneri Buffetaut 1981, known from a single specimen (MNHN GDF-700), is a fossil crocodylian from the Aptian (Middle Cretaceous) of Tegama Basin (Elrhaz Fm). The fossil material, limited to rostrum and mandibles, was found at Gadoufaoua (Agadez, Niger). Despite its mention in a number of works, the specimen still lacks a detailed description. A reappraisal of the type specimen allowed the identification of new data on the maxilla, dentition and ectopterygoid, shared exclusively with A. gomesii. Other members of the genus are known from Argentina (A. patagonicus, A. buitreraensis) and Madagascar (A. tsangatsangana). The observations contrast with the prevalent phylogenetic position in the literature, where A. wegneri is depicted as the most basal member of its clade. Results show that character conflict comes from: (i) lack of information on other species of Araripesuchus, and (ii) the prevalence of young over mature specimens in the genus. The specific morphology of the ornamentation was used to access the ontogenetic stage of the holotype, showing that although GDF-700 is a small individual, it was not an immature. The morphology of rostrum, choanae and the ectopterygoid suggests that Araripesuchus (and possibly Uruguaysuchus) are more closely related to peirosaurids than to notosuchids, supporting previous phylogenetic works. Nevertheless, the pattern of dentition shows convergence with Upper Cretaceous notosuchians from South America. The phylogenetic relationships of Araripesuchus constitute important data, since they support particular models of paleobiogeography.