Systematics

Systematics

Family tree of the Hadrosauroidea. Representative genera of each tribe are shown to scale.

Taxonomy

The family Hadrosauridae was first used by Edward Drinker Cope in 1869. Since its creation, a major division has been recognized in the group, between the (generally crested) subfamily Lambeosaurinae and (generally crestless) subfamily Hadrosaurinae. Phylogenetic analysis has increased the resolution of hadrosaurid relationships considerably (see Phylogeny below), leading to the widespread usage of tribes (a taxonomic unit below subfamily) to describe the finer relationships within each group of hadrosaurids. However, many hadrosaurid tribes commonly recognized in online sources have not yet been formally defined or seen wide use in the literature. Several were briefly mentioned but not named as such in the first edition of The Dinosauria, under informal names. In this 1990 reference, "gryposaurs" included Aralosaurus, Gryposaurus, Hadrosaurus, and Kritosaurus; "brachylophosaurs" included Brachylophosaurus and Maiasaura; "saurolophs" included Lophorhothon, Prosaurolophus, and Saurolophus; and "edmontosaurs" included Anatotitan, Edmontosaurus, and Shantungosaurus.[4]

Lambeosaurines have also been split into Parasaurolophini (Parasaurolophus) and Corythosaurini (Corythosaurus, Hypacrosaurus, and Lambeosaurus).[5] Corythosaurini and Parasaurolophini as terms entered the formal literature in Evans and Reisz's 2007 redescription of Lambeosaurus magnicristatus. Corythosaurini is defined as all taxa more closely related Corythosaurus casuarius than to Parasaurolophus walkeri, and Parasaurolophini as all those taxa closer to P. walkeri than to C. casuarius. In this study, Charonosaurus and Parasaurolophus are parasaurolophins, and Corythosaurus, Hypacrosaurus, Lambeosaurus, Nipponosaurus, and Olorotitan are corythosaurins.[6]

The following taxonomy includes dinosaurs currently referred to the Hadrosauridae and its subfamilies. Hadrosaurids that were accepted as valid but were not placed in a cladogram at the time of the 2004 review in The Dinosauria,[7] or, in the case of lambeosaurines, the 2007 redescription of Lambeosaurus magnicristatus,[6] are included at the highest level to which they were placed (either then, or in their description if they postdate the papers used here).