A NEW SPECIES OF SHANTUNGOSUCHUS FROM THE LOWER CRETACEOUS OF INNER-MONGOLIA (CHINA), WITH COMMENTS ON S-CHUHSIENENSIS YOUNG, 1961, AND THEPHYLOGENETIC POSITION OF THE GENUS

Shantungosuchus hangjinensis, sp. nov. is described on the basis of a partial skull and lower jaws from the Lower Cretaceous Luohandong Form ation, Zhidan Group of Hangjin Qi, Inner Mongolia (China). S. chuhsien ensis, from the ?Upper Jurassic deposits of Shandong province, eastern China, is re-examined. Shantungosuchus is primarily distinguished fro m all other crocodyliforms by a short premaxilla/maxillary portion of the skull, a transversely broad shelf of the jugal ventral to the orbi t, a pair of posterolaterally divergent ridges on the pterygoid, a pai r of large basisphenoid depressions, the exclusion of the angular from posterolateral surface of the mandible, and the superficially asymmet rical appearance of the two dentaries in the symphysial region. Shantu ngosuchus is probably also unique in possessing a quadratojugal fossa, a leaf-shaped palatine separated from the suborbital fenestra, a pron ounced coronoid projection of the surangular, and a tibia longer than the femur. A phylogenetic analysis of the early crocodyliforms represe nted by better preserved material tentatively indicates that the Proto suchia is monophyletic and strongly suggests that Shantungosuchus is c losely related to the Protosuchidae rather than to the Atoposauridae o f the ''Mesosuchia.''