Macrogryphosaurus (meaning "big enigmatic lizard") is a genus of basal iguanodont dinosaur from the Turonian-early Coniacian age Upper Cretaceous Portezuelo Formation (Neuquén Group) of Patagonia, Argentina. It was described by Jorge Calvo and colleagues, with M. gondwanicus as type species (referring to the animal coming from Gondwana).