A thick-skulled theropod (Dinosauria, Saurischia) from the Upper Cretaceous of Morocco with implications for carcharodontosaurid cranial evolution Andrea Cau a, * , Fabio M. Dalla Vecchia b , Matteo Fabbri c a Museo Geologico ‘Giovanni Capellini’, Via Zamboni 63, I-40127 Bologna, Italy b Institut Catalá de Paleontologia ‘M. Crusafont’, C/ Escola Industrial 23, E-08201 Sabadell, Spain c Dipartimento di Scienze della Terra, Università degli Studi di Firenze, Via La Pira 4, I-50121 Firenze, Italy article info Article history: Received 15 July 2012 Accepted in revised form 26 September 2012 Available online xxx Keywords: Carcharodontosauridae Cenomanian Frontal Morocco Sauroniops pachytholus abstract In this study, we erect Sauroniops pachytholus gen. et sp. nov., a large-bodied theropod dinosaur from the Cenomanian (Upper Cretaceous) of Morocco, on the basis of an almost complete frontal showing a unique combination of features including a nasoefrontal suture extended along 40% of the frontal length, a thick dome in the anterolateral corner of the dorsal surface, a trapezoidal prefrontal facet that is restricted to the anterodorsal margin of the lateral surface of the frontal with no participation in the orbital roof and separated from the lacrimal facet by a narrow vertical lamina, a hypertrophied ‘D-shaped’ lacrimal facet that is four times the anterior depth of the postorbital facet, and a raised posteromedial margin of the dorsal surface describing a saddle with the anterolateral dome and confluent with a series of anteromedial rugosities. Phylogenetic analysis found robust support for placing Sauroniops among the basal carcharodontosaurids and related to Eocarcharia, showed that some of the unusual features of the new theropod were convergently acquired by abelisaurids, and revealed a mosaic pattern in the evolution of the carcharodontosaurid skull table. The frontals of Sauroniops and Carch- arodontosaurus, both from the ‘Kem Kem compound assemblage’ of Morocco, show comparable size but differ in the extent of the nasoefrontal articulation, the shape and disposition of the prefrontal and lacrimal articulations, the development of dorsal ornamentation and the morphology of the supra- temporal fossa. Among carcharodontosaurids, the skull table developed unique configurations among each lineage and appears diagnostic at the species-level. The dome-like frontal in Sauroniops may indicate head-butting behaviour in this taxon or evolved for visual display. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Carcharodontosauridae is a clade of theropod dinosaurs mainly known from the AptianeTuronian of Africa, South America, North America and Asia, including among the largest-known hyper- carnivorous terrestrial vertebrates (Stromer, 1931; Stovall and Langston, 1950; Coria and Salgado, 1995; Sereno et al., 1996; Coria and Currie, 2002, 2006; Novas et al., 2005b; Brusatte and Sereno, 2007; Sereno and Brusatte, 2008; Brusatte et al., 2010b). Carchar- odontosaurids probably originated in the Late Jurassic (Rauhut, 2011) and reached a cosmopolitan distribution no later than the Early Cretaceous (Brusatte et al., 2010b). Carcharodontosaurids possess a highly distinctive, apomorphic skeletal morphology relative to related non-coelurosaurian tetanuran lineages (Carrano et al., 2012), showing lateral sculpturing of the facial bones, extensive fusion among the skull roof and braincase elements, blade-like teeth with distinctive enamel ornamentation, extensive pneumatization of the axial skeleton, and the reorganisation of the pelvis and hind limb as probable load-bearing adaptation (Sereno et al., 1996; Coria and Currie 2002, 2006; Novas et al., 2005b; Eddy and Clarke, 2011; Bates et al., 2012). Due to the numerous autapomorphies in their skeletons, carcharodontosaurids can be identified even from isolated bones (e.g., Russell, 1996; Rauhut, 2011). Cau et al. (2012) described an isolated frontal of a large-sized theropod dinosaur from the Cenomanian (Upper Cretaceous) of Morocco and interpreted it as belonging to a carcharodontosaurid distinct from the sympatric Carcharodontosaurus, based on its unique morphology and on the result of a phylogenetic analysis placing the new specimen in a basal lineage of the Carchar- odontosauridae. A comparison with the other theropod lineages known from the Cenomanian of Morocco was provided (Cau et al., 2012), and no support for alternative interpretations was recov- ered. A re-examination of the specimen led us to review both its * Corresponding author. E-mail address: cauand@gmail.com (A. Cau). Contents lists available at SciVerse ScienceDirect Cretaceous Research journal homepage: www.elsevier.com/locate/CretRes 0195-6671/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.cretres.2012.09.002 Cretaceous Research xxx (2012) 1e10 Please cite this article in press as: Cau, A., et al., A thick-skulled theropod (Dinosauria, Saurischia) from the Upper Cretaceous of Morocco with implications for carcharodontosaurid cranial evolution, Cretaceous Research (2012), http://dx.doi.org/10.1016/j.cretres.2012.09.002