resemblance to specimens of the genus Tanius, but eventually discarded both ideas. C. C. Young revived the latter idea, and assigned the material to Tanius. Regarding Mandschurosaurus he agreed with Gilmore's referral of his species to the genus, and went further to say it's possible it actually represents the same species as M. amurensis. Anatoly K. Rozhdestvensky, in the 1960s, considered a different solution; that Bactrosaurus was in fact a hadrosaurine, not a lambeosaurine. Furthermore, he thought that M. mongoliensis was merely a synonym of his hadrosaurine Bactrosaurus, a position he would continue to hold in future works. Future authors would disagree, reaffirming the two hadrosaurs as distinct and Bactrosaurus as a lambeosaur. Reclassification as Gilmoreosaurus and subsequent research The next major change in taxonomy would come from Michael K. Brett-Surman, who was in the process of a revision of the entire hadrosaur family. Firstly, he provided a novel diagnosis for the species in his 1975 master's thesis. However, Brett-Surman considered Mandschurosaurus amurensis to be dubious; he therefore thought it necessary to give Gilmore's species a new generic name. As such, he coined the genus Gilmoreosaurus in 1979, honouring Gilmore, and created the new combination Gilmoreosaurus mongoliensis. He considered Gilmore's two hadrosaurs to be of great importance, something he elaborated on in a short 1980 paper. He described the anatomy of Gilmoreosaurus as "partly iguanodont and partly hadrosaurine" and saw it as the ancestral form of hadrosaurine; Bactrosaurus, likewise, was seen as the ancestral lambeosaur. It was based in part on the two species, as well as on Probactrosaurus, that he concluded that hadrosaurs had originated in Asia. One thing that interested Brett-Surman greatly was the similarity of the Asian fauna to the later fauna of the North American Two Medicine Formation; Gilmore had, in his 1933 paper, made similar comments about the nature of Asian and American faunas. The 1980 paper noted that a lot of additional material from Iren Dabasu was never described by Gilmore, especially material pertaining to juvenile material. Brett-Surman reported that he and John R. Horner were at work investigating this material to form a more complete understanding of the formations' fauna. Referring to this, he concluded the paper by saying: "Although no more expeditions are possible to Mongolia by this time, light will be shed on the natural history of dinosaurs by further scientific expeditions to the basement of the natural history museum". Halszka