A dentary fragment that preserves several teeth in situ of an ornithopod dinosaur from the Lower Cretaceous of Salas de los Infantes (Burgos, Spain) is described. The general aspect and the conservation of the rock associated with the fossil suggest that it would come from the Pinilla de los Moros Formation (upper Hauterivian-lower Barremian). The material takes part, together with other fossils of dinosaurs and crocodilians, of a collection gathered at the end of the 1960’s and deposited nowadays in the Institut für Geowissenschaften of the University of Tübingen (Germany). The dentary teeth exhibit a distal primary ridge and a mesial secondary ridge, as typically in basal iguanodontoids. Nevertheless, some teeth show a single subcentral carina and lack subsidiary ridges, as in hadrosaurids. Unlike hadrosaurids, however, the Salas specimen has probably one functional tooth and one replacement crown per dentary tooth position, retaining the plesiomorphic state present in basal iguanodontoids. Due to the fragmentary nature of the material, it is provisionally assigned to Iguanodontoidea indet