An articulated skeleton of a hadrosauroid dinosaur, Tethyshadros insularis n. gen., n. sp., was recovered from the Liburnian Formation (uppermost Cretaceous) of Villaggio del Pescatore in the Trieste Province of northeastern Italy. One of the most complete dinosaur fossil ever found, it shows for the first time the entire morphology of a hadrosauroid phylogenetically close to, but outside the North American and Asiatic hadrosaurids. It lived on an island developed on a carbonate platform in the Tethys Ocean and the small size of the specimens suggests that it may be an insular dwarf. The skeleton has many peculiarities including cursorial adaptations, and a mix of derived and primitive features. European hadrosauroids probably did not evolve by vicariance nor did they colonize the European Archipelago from North America, but rather came from Asia by island hopping.