Taxonomic revision of the dyrosaurid assemblage (Crocodyliformes: Mesoeucrocodylia) from the Paleocene of the Iullemmeden Basin, West Africa

The dyrosaurids of the Iullemmeden Basin (West Africa) are mainly represented by two genera, Hyposaurus and Rhabdognathus. Hyposaurus has been recognized in the Paleocene of Mali and Nigeria with two species, H. nopcsai and H. wilsoni. Diagnostic characters given by previous authors for these species do not enable their distinction from each other, nor from North American species. It is therefore reasonable to consider H. nopcsai and H. wilsoni as nomina dubia. In 1930, Swinton erected the new genus and species Rhabdognathus rarus on the basis of mandibular remains, and Buffetaut referred a skull to this species in 1980. A new skull was described in 2002 by Brochu et al., and referred to Rhabdognathus sp. Unfortunately, it is impossible to refer either skull to the type species, the mandibular remains having no diagnostic characters at the specific level. Thus, R. rarus is a nomen dubium, and two new names are erected for the two skulls: R. keiniensis n. sp. and R. aslerensis n. sp., all the mand...