related, whereas others have not, instead finding it closer to Brachylophosaurus, Edmontosaurus, Gryposaurus, and Maiasaura. History of classification In 1918, Lawrence Lambe revised the classifications of Hadrosauridae (then Trachodontidae). He invalidated the family name and Trachodontinae, replacing them with Hadrosauridae and Hadrosaurinae. The other subfamily in Hadrosauridae then was Saurolophinae, which included Stephanosaurus (= Lambeosaurus), Cheneosaurus, Corythosaurus, Prosaurolophus, and Saurolophus. Lambe, in 1920, split Saurolophinae and found only two genera remaining in it, Prosaurolophus, and the type genus. The previous genera were then reclassified into Stephanosaurinae or Hadrosaurinae. In 1928, Prosaurolophus was assigned to Saurolophinae by Franz Nopcsa. The group contained hadrosaurids with a "males with median horn-like protuberance on the skull" and "very numerous teeth", found by Nopsca to be Parasaurolophus, Saurolophus, and Prosaurolophus. In 1954, Charles Sternberg reevaluated the genera in Hadrosauridae, invoking the probability that Saurolophinae should be sunk into Hadrosaurinae. This greatly changed the classifications of the family, as the "saurolophines" were kept separate because of their supposedly "footed" ischium. Sternberg identified that the "footed" ischium assigned to Saurolophus was not found with the holotype, and was only assigned to it because of the location of the find. Also, he noted that William Parks (1924) found a complete skeleton of Prosaurolophus clearly showing an "unfooted" ischium, which Sternberg realized meant that it was unlikely that Saurolophus possessed a "footed" ischium. Sternberg's reevaluation led to the abandonment of Saurolophinae. Young (1958) found that the subfamily Saurolophinae, however, was not to be abandoned, and in it placed his new genus Tsintaosaurus, as well as Prosaurolophus and Saurolophus, and also Kritosaurus (which included Gryposaurus and excluded K. navajovius). Two years previous, Friedrich von Huene separated Saurolophinae from Hadrosauridae, naming Saurolophidae. Saurolophidae was a family in Huene's Hadrosauria, including the genera Prosaurolophus, Saurolophus, and the probably unrelated Bactrosaurus. Another author to support the separation of Saurolophinae was John Ostrom (1961). Ostrom found that the saurolophines Brachylophosaurus, Prosaurolophus, and Saurolophus all possessed a "pseudonarial crest", a feature which united them, while distinguishing them from hollow-crested lambeosaurines. Hopson (1975) supported the division of Hadrosauridae into two subfamilies, Hadrosaurinae and Lambeosaurinae, and was first to suspect what modern analyses find. Hopson found that Hadrosaurinae could clearly be divided into groups, the "kritosaurs", the "edmontosaurs", and the "saurolophines", including Prosaurolophus, Saurolophus, Tsintaosaurus and Lophorhothon, and intermediate between the "kritosaurs" and "saurolophines". Brett-Surman (1975) also followed Sternberg with sinking Saurolophinae into Hadrosaurinae, and like Hopson,