Juvenile ornithopod (Dinosauria: Rhabdodontidae) remains from the Upper Cretaceous (Lower Campanian, Gosau Group) of Muthmannsdorf (Lower Austria) Des restes d’ornithopode juvénile (Dinosauria : Rhabdodontidae) du Crétacé supérieur (Campanien inférieur, Groupe de Gosau) de Muthmannsdorf (Autriche méridionale) Reste eines juvenilen Ornithopoden (Dinosauria: Rhabdodontidae) aus der Oberkreide (Unteres Campanium, Gosau-Gruppe) von Muthmannsdorf (Niederösterreich) Sven Sachs a, * , Jahn J. Hornung b a Institut für Paläontologie, Freie Universität Berlin, Haus D, Malteser Strasse 74-100, 12249 Berlin, Germany b Institut für Geologie und Paläontologie, Universität Hannover, Callinstrasse 30, 30167 Hannover, Germany Received 22 July 2004; accepted 24 January 2005 Available online 06 March 2006 Abstract The fragmentary remains of a juvenile rhabdodontid ornithopod from the Coal-bearing Complex of the Gosau Group (Lower Campanian, Grünbach syncline) at Muthmannsdorf near Wiener Neustadt, Lower Austria are revised. The material, probably belonging to a single individual, includes a right dentary (lectotype of Iguanodon suessi Bunzel, 1871, designated herein), teeth, a fragmentary parietal, fragments of scapula, ? radius, femur, tibia, two vertebrae (lost) and a manual ungual. The lectotype dentary does not provide clear autapomorphies or sufficient diagnostic features to determine its position within the Rhabdo- dontidae at generic level. By this “Iguanodon suessi” Bunzel, 1871 and the genus “Mochlodon” Seeley, 1881, to which it was latter referred as type species, cannot be characterized sufficiently by differential diagnosis and these are best considered nomina dubia. Based upon combined character comparisons (mainly postcranial features) the Muthmannsdorf ornithopod is referred herein to Zalmoxes Weishampel, Jianu, Csiki and Norman, 2003, a genus so far known from the late Maastrichtian of Romania. It probably but not evidently represents a yet unnamed species, most closely related to Zalmoxes shqiperorum Weishampel, Jianu, Csiki and Norman, 2003. At the present state of knowledge the Austrian material is not further diagnostic at the species level and kept in open nomenclature as Zalmoxes sp. © 2006 Elsevier SAS. All rights reserved. Résumé Les fragments d’ornithopode rhabdodontidé juvénile du Groupe de Gosau (Campanien inférieur, syncline de Grünbach) à Muthmannsdorf, près de Wiener Neustadt en Autriche méridionale, sont redécrits. Le matériel comprend un dentaire droit (lectotype de Iguanodon suessi Bunzel, 1871), des dents, ainsi que des fragments de pariétal, scapula, ? radius, fémur, tibia, deux vertèbres perdues et une phalange unguéale de la main. Le lectotype de Iguanodon suessi Bunzel, 1871 ne montre pas d’autapomorphies ni de caractères diagnostiques suffisants pour déterminer la position de ce genre au sein des Rhabdodontidae. « Iguanodon suessi » et le genre « Mochlodon » Seeley, 1881, auquel l’espèce-type fût plus tardivement rapportée, ne peuvent donc être suffisamment définis par une diagnose différentielle, et sont considérés comme des nomina dubia. http://france.elsevier.com/direct/GEOBIO/ Geobios 39 (2006) 415–425 * Corresponding author. E-mail address: Sachs.Pal@gmx.de (S. Sachs). 0016-6995/$ - see front matter © 2006 Elsevier SAS. All rights reserved. doi:10.1016/j.geobios.2005.01.003