[6] Hadrosauromorpha was first given a phylogenetic definition by Norman (2014 and 2015) as hadrosauroid taxa closer to Edmontosaurus regalis than Probactrosaurus gobiensis.

[2] Norman (2014) created his own analysis, which includes 105 different morphological characters and 27 select ornithopod taxa.

[8] Morelladon Mantellisaurus Equijubus Bolong Ouranosaurus Jinzhousaurus Xuwulong Altirhinus Koshisaurus Gongpoquansaurus Batyrosaurus Proa Ratchasimasaurus Penelopognathus Sirindhorna Zuoyunlong Probactrosaurus Eolambia Jintasaurus Jeyawati Protohadros Datonglong Tethyshadros Levnesovia Nanyangosaurus Bactrosaurus Gilmoreosaurus Orthomerus Tanius Zhanghenglong Plesiohadros Shuangmiaosaurus Hadrosauridae Probactrosaurus was selected as the outgroup to Hadrosauromorpha because of numerous differences that Norman (2014) thought to be significant.

The tooth crowns in the dentary are asymmetrical and have multiple vertical ridges; there is a foramen in the surangular; and the quadrate bone has a more prominent depression for the articulation of the jugal.

Probactosaurus, however, possesses the basal condition of having a small, conical pollex, like in earlier ornithopods such as Iguanodon or Hypselospinus.