The cranial skeleton of the enigmatic gliding neodiapsid reptile Coelurosauravus elivensis (Lower Sakamena Formation, Lopingian, Southwestern Madagascar) is re-described in detail. All previously referred specimens are re-examined under both direct observations and Reflectance Transformation Imaging. Their exquisite preservation yields detailed three-dimensional information on the outline of individual bones and their osteological relationships, which are missing in the Laurasian remains. In contrast to previous studies, the ontogenetic maturity of all specimens is re-affirmed. Previously unidentified elements of the palate, braincase and mandible are described, and a novel reconstruction is proposed, including the first palatal reconstruction in a weigeltisaurid reptile.C. elivensis has the smallest skull of all weigeltisaurids and differs from other species in its facial ornamentation, parietosquamosal frill and larger anterior maxillary dentition. We also provide extensive comparisons with contemporaneous reptiles, possibly closely related taxa and more recent analogs, as well as a preliminary discussion of the functional anatomy of the peculiar cranial morphology of weigeltisaurids. The cranial skeleton is a truss construction with large orbits and temporal fenestrae. By analogy with extant chamaeleonids, the elongate parietosquamosal frill is associated with an increase in length and diameter of the temporal jaw adductors, resulting in an increased gape and/or bite force and speed. Additionally, the spikes and frills of weigeltisaurids most likely served as a display and defensive structure.

A systematic revision of the temnospondyl 'Metoposaurus' azerouali Dutuit from the Late Triassic of the Argana Basin (Western High Atlas, Morocco) is presented. The type material is redescribed in detail, and a preliminary phylogenetic analysisthe first one dealing with all metoposaurid speciesis also conducted in order to test its position within the Metoposauridae. Our analysis places 'Metoposaurus' azerouali as sister-taxon to Arganasaurus lyazidi in a robust clade supported by two unambiguous synapomorphies (bulge-like tabular horn and exoccipital process visible in dorsal view) and two ambiguous synapomorphies (cultriform process of uniform width and subtriangular posterior Meckelian fenestra). We therefore propose the new combination Arganasaurus azerouali comb. nov. for the species 'M.' azerouali. Our analysis also confirms that the central Laurasian genus Metoposaurus is monophyletic but not the genus Koskinonodon, which deserves its own systematic revision. By consequent, the Late Triassic rich vertebrate fauna from the Argana Basin comprises the metoposauroid Almasaurus habazzi, the basal metoposaurid Dutuitosaurus ouazzoui, and the genus Arganasaurus which is represented by the type species A. lyazidi and A. azerouali comb. nov. Combined with the stratigraphical and geographical occurrences of the taxa, our phylogenetic analysis suggests that metoposaurids may have appeared during the Longobardian (late Ladinian) in central Pangea. Their diversification may be linked to the Carnian Pluvial Episode. At least, their extinction may have occurred during the Rhaetian because of the aridification of the climate and/or competition with amniotes.

The postcranial skeleton of the gliding neodiapsid reptile Coelurosauravus elivensis (Lower Sakamena Formation, late? Permian, southwestern Madagascar) is redescribed in detail based on all previously referred specimens. The exquisite preservation of the material provides three-dimensional details of the individual bones, which are missing in the Laurasian weigeltisaurid material. A new skeletal reconstruction of C. elivensis is proposed including the first reconstruction of a weigeltisaurid reptile in lateral view. The reexamination of the material highlights interspecific differences in the postcranium of weigeltisaurids, in particular in the trunk and patagial spars. These animals have long been considered as arboreal and gliding reptiles. However, new information on the postcranium of C. elivensis reveals strong similarities with both extant and extinct quadrupeds specialized for a clinging arboreal lifestyle. Additionally, the presence of an additional phalanx in the fifth digit of the manus is now attested for all weigeltisaurids where this region is preserved. We suggest that this morphology could have allowed weigeltisaurids to grasp their patagium as observed in the extant gliding agamid Draco. Weigeltisaurids are thus the earliest known gliding vertebrates and some of the first tetrapods with an obligatory arboreal lifestyle, but also represent the only known vertebrates with a hyperphalangy aligned with a gliding apparatus.

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