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Hadrosauroidea is a clade or superfamily of ornithischiandinosaurs that includes the "duck-billed" dinosaurs, or Hadrosauridae, and all dinosaurs more closely related to them than to Iguanodon. Their remains have been recovered in Asia, Europe, Africa and the Americas. Many primitive hadrosauroids, such as the Asian Probactrosaurus and Altirhinus, have traditionally been included in a paraphyletic (unnatural grouping) "Iguanodontidae". With cladistic analysis, the traditional Iguanodontidae has been largely disbanded, and probably includes only Iguanodon and perhaps its closest relatives.
Classification
Hadrosauroidea was given a formal phylogenetic definition in the PhyloCode by Daniel Madzia and colleagues in 2021 as "the largest clade containing Hadrosaurus foulkii, but not Iguanodon bernissartensis". The cladogram below follows an analysis by Andrew McDonald, 2012, and shows the position of Hadrosauroidea within Styracosterna:
Wu Wenhao & Pascal Godefroit (2012). "Anatomy and relationships of Bolong yixianensis, an Early Cretaceous iguanodontoid dinosaur from western Liaoning, China". In Godefroit, P. (ed.). Bernissart Dinosaurs and Early Cretaceous Terrestrial Ecosystems. Indiana University Press. pp. 293–333.
