Disarticulated material from the Late Triassic Timezgadiouine Formation in the Argana Basin of Morocco represents a new taxon of silesaurid dinosauromorph, Diodorus scytobrachion gen. et sp. nov. D. scytobrachion can be distinguished from other silesaurids by the presence of anteriorly−canted teeth that decrease in size towards the anterior end of the dentary and a distinct lateral ridge running parallel to the dentary alveolar margin. In a phylogenetic analysis, D. scytobrachion is recovered as the sister−taxon to the Brazilian Sacisaurus agudoensis, nested deep within Silesauridae. This new taxon provides further evidence of a near−cosmopolitan range for basal dinosauriforms in the Late Triassic and further demonstrates the disparity of dental morphologies within Silesauridae.

Key words: Dinosauromorpha, Silesauridae, Triassic, North Africa, Morocco.

Christian F. Kammerer [ckammerer@amnh.org ], Division of Paleontology and Richard Gilder Graduate School, American Museum of Natural History, New York, NY 10024, USA; current address: [christian.kammerer@mfn−berlin.de], Museum für Naturkunde, Invalidenstraße 43, 10115 Berlin, Germany; Sterling J. Nesbitt [nesbitt@jsg.utexas.edu], Jackson School of Geosciences, The University of Texas at Austin, Austin, TX 78712, USA; Neil H. Shubin [nshubin@uchicago.edu ], Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637, USA.