Penélope Cruzado-Caballeroa, Leonardo S. Filippi, Ariel H. Méndez, Alberto C. Garrido and Rubén D. Juárez Valieri

Ornithopods are the least known dinosaurs within the Upper Cretaceous record of Argentina. For this rea-son every new record is very important to know their evolution in South America. Here, we describe a new remain of an indeterminate ornithopod recovered in the Petrobrasaurus quarry of the Puesto Hernández area, northeastern Neuquén province (Argentina), late Coniacian–early Santonian in age. MAU-Pv-PH-458 is the northernmost bone record of an ornithopod in Argentina. This is a fragmentary neural arch fromthe middle section of the dorsal series of similar size to Macrogryphosaurus gondwanicus. MAU-Pv-PH-458 has typical ornithopod characters such as a lateromedial narrow neural spine and transverse processes dorsoposteriorly to posteriorly oriented. It shares with Macrogryphosaurus the presence of a deep cannel between the bases of the postzygapophysis, which is a continuation of the channel that separates the postzygapophyses in posterior view. MAU-Pv-PH-458 increases the ornithopod record from the Plottier Formation.