A well-preserved dentary from the Late Cretaceous of Neuquén Province, Argentina, represents a new taxon of sebecosuchian crocodyliform, Pehuenchesuchus enderi. The specimen retains a number of diagnostic characters and is referable to Sebecosuchia on the basis of two derived features (a longitudinal groove on the lateral surface of the dentary and a sigmoidal tooth row in dorsal view). The new taxon differs from all other sebecosuchians by possessing laterally compressed teeth that lack serrated carinae. A phylogenetic analysis of 30 crocodyliform taxa and two character-taxon matrices, which include many putative sebecosuchians, supports a monophyletic Sebecosuchia. In both analyses, Pehuenchesuchus enderi was resolved as the sister taxon to all other sebecosuchians. A clear division of Sebecosuchia into Sebecidae and Baurusuchidae was not supported.