Saurolophinae was first defined as a
clade in a 2010 phylogenetic analysis by Prieto-Márquez. In a 2023 study, Alarcón-Muñoz et al. implemented an updated version of the phylogenetic matrix of Rozadilla et al. (2022) to analyze the relationships of saurolophines and hadrosaurids. The results of their
phylogenetic analyses of Saurolophinae are displayed in the
cladogram below.
Subgroups The
clade Brachylophosaurini was defined by Terry Gates and colleagues in 2011 as "Hadrosaurine ornithopods more closely related to
Brachylophosaurus,
Maiasaura, or
Acristavus than to
Gryposaurus or
Saurolophus". In 2021, Madzia et al. registered Brachylophosaurini in the PhyloCode and formally defined it as "The largest clade containing
Brachylophosaurus canadensis but not
Edmontosaurus regalis,
Hadrosaurus foulkii,
Kritosaurus navajovius and
Saurolophus osborni". The name "Kritosaurini" was first mentioned in 1955 by
Lapparent &
Lavocat, where they mentioned "'Kritosaurinés" as a group of hadrosaurids containing only
Kritosaurus, which was thought of as a
senior synonym of
Gryposaurus at the time. In 1989,
Michael Brett-Surman proposed the name Kritosaurini as a
tribe of
hadrosaurines that contained
Aralosaurus,
Brachylophosaurus,
Hadrosaurus, and
Kritosaurus (including
Gryposaurus). It was not until 2014 that Albert Prieto-Márquez officially defined and diagnosed Kritosaurini as the most exclusive clade of hadrosaurids containing
Kritosaurus navajovius,
Gryposaurus notabilis, and
Naashoibitosaurus ostromi. Madia et al. (2021) defined the term under PhyloCode as "the largest clade containing
Kritosaurus navajovius but not
Brachylophosaurus canadensis,
Edmontosaurus regalis,
Hadrosaurus foulkii,
Saurolophus osborni. In a study the following year, Alarcón-Muñoz et al. implemented an updated version of the phylogenetic matrix of Rozadilla et al., proposing the name
Austrokritosauria for the clade of entirely South American saurolophines closely related to kritosaurins. This clade was defined as "the most inclusive clade containing
Huallasaurus but not
Gryposaurus". ==Palaeobiogeography==