Hadrosauroidea
Hadrosauroidea consists of Hadrosaurus foulkii and all taxa most closely related to it than to Iguanodon bernissartensis, including Hadrosaurinae (represented solely by Hadrosaurus) and Saurolophidae. The latter is defined as the last common ancestor of Saurolophus osborni, Lambeosaurus lambei, and all its descendants, which includes the two major hadrosaurid clades: Saurolophinae and Lambeosaurinae. (Prieto-Márquez (2010)