A new carnivorous cynodont from the Ischigualasto formation (late Triassic, Argentina), with comments on eucynodont phylogeny

The nearly complete skull of a recently discovered carnivorous eucynodont, Ecteninion lunensis, gen. et sp. nov., is described. This is the first new genus of carnivorous cynodont reported from the Late Triassic (middle Carnian) Ischigualasto Formation of northwestern Argentina, and is unique to the formation. Diagnostic features include partially differentiated cheek teeth that overlap in an imbricate pattern, elongate braincase and parietal crest, pronounced lateral expansion of the braincase, sagittal crest that overhangs the occipital plate in dorsal view, gracile postorbital bars, short osseous secondary palate, maxilla excluded from the border of the subtemporal fenestra, palatine and orbitosphenoid that contribute to the medial orbital wall, post-temporal foramen enclosed within the tabular, squamosals that nearly meet at the posterior end of the sagittal crest, narrow and deep groove for the external auditory meatus, jaw articulation located at the anterior base of the zygomatic arches, and cavum epiptericum extensively floored by the prootic. A phylogenetic analysis of the Eucynodontia, using craniodental characters, places Ecteninion lunensis in a trichotomy with Probainoganthus and a monophyletic clade consisting of Tritylodontidae, Tritheledontidae, and Morganucodon.