The last known freshwater coelacanths: New Late Cretaceous mawsoniid remains (Osteichthyes: Actinistia) from Southern France.

Coelacanths are iconic fishes represented today by a single marine genus. The group was a little bit more diversified in the Mesozoic, with representatives in marine and continental environments in the Late Cretaceous. Here we describe isolated skull bones of the last know freshwater coelacanths found in several fossil sites from the Early Campanian to the Early Maastrichtian of Southern France (in the Departments of Aude, Bouches-du-Rhône, Hérault, and Var). The sample does not allow distinguishing different species, and all material is referred to Axelrodichthys megadromos Cavin, Valentin, Garcia originally described from the locality of Ventabren in Southern France. A reconstruction of the skull is proposed. Previously unrecognized features are described, including parts of the postparietal portion of the skull, of the suspensorium and of the mandible. The new data confirm the assignation of the species to the mawsoniids, and more specifically to Axelrodichthys. A cladistic analysis scoring new character states provides a similar topology than a previous analysis, i.e. A. megadromos is placed in a polytomy with Axelrodichthys araripensis and Lualabaea lerichei, two species from the Early Cretaceous of Brazil and from the Late Jurassic of the Democratic Republic of the Congo, respectively. A. megadromos appears to have been restricted to freshwater environments, to the contrary of oldest Western Gondwanan representatives of the family that were able to live in brackish and marine waters. A. megadromos is the last representative of the mawsoniids and its occurrence in Europe is probably the result of a dispersal event from Western Gondwana that happened somewhen in the Cretaceous. Based on the available data, the mawsoniids went extinct in the mid-Maastrichthian, i.e. before the end-Cretaceous mass extinction. But it is possible that the fossil record of this family, which has been only recently recognized in Late Cretaceous European deposits, will geographically and stratigraphically widen with further discoveries.

An Unexpected Early Rhabdodontid from Europe (Lower Cretaceous of Salas de los Infantes, Burgos Province, Spain) and a Re-Examination of Basal Iguanodontian Relationships.

Disarticulated and incomplete remains from a new diminutive ornithopod are described. They come from the Cameros Basin in the north of Spain and were collected from the red clays of the Castrillo de la Reina Formation, ranging from Upper Barremian to Lower Aptian. The new ornithopod described here is slender and one of the smallest ever reported. An up-to-date phylogenetic analysis recovers this taxon as a basal iguanodontian. Its unique combination of characters makes it more derived than slender ornithopods like Hyphilophodon and Gasparinisaura, and bring very interesting insights into the basal iguanodontian phylogeny. Though possessing a minimum of three premaxillary teeth, this taxon also bears an extensor ilio-tibialis groove on the distal part of its femur. Moreover, its dentary and maxillary teeth are unique, remarkably similar to those regarded as having a "rhabdomorphan" affinity. This unknown taxon is suggested to be a stem taxon within Rhabdodontidae, a successful clade of basal iguanodonts from the Late Cretaceous of Europe. The Gondwanan ornithopods share the strongest affinities with this family, and we confirm Muttaburrasaurus as a sister taxon of the Rhabdodontidae within a newly defined clade, the Rhabdodontomorpha.