Osmólska and Teresa Maryańska published a paper in 1981 which focused on Saurolophus angustirostris, but also provided comments on Asian hadrosaurs as a whole. Among these comments, they returned to the issue of the skull material. They disagreed the otherwise monospecific nature of the quarry (i.e. only one species seeming to be present) was stronger evidence than the discordant anatomy of the material. As such, they revived Young's model and tentatively assigned the material to Tanius, which they felt it fit most closely. They noted the skull may prove to belong to either Gilmoreosaurus or Bactrosaurus after additional research. This would come to be in 1985, when Horner and David B. Weishampel would re-examine the material of both Iren Dabasu genera as well as material Gilmore never described, as had been indicated by Brett-Surman. Osmólska provided feedback on their study. The relevant new material was remains that the authors considered to be "clearly lambeosaurine" in nature, and so referrable to Bactrosaurus. As they could not possibly fit with the skull material, they concluded said material wasn't from the genus. Instead, they decided that it, congruent with its seemingly hadrosaurine nature, belonged to Gilmoreosaurus. At the end of the paper they reaffirmed the importance of both genera as the best record of early hadrosaurs. The issue would finally be put to rest by Pascal Godefroit and colleagues in 1998, when they published a study describing newly discovered Bactrosaurus material. They returned to the original position of Gilmore, that the possibility of two taxa in the Bactrosaurus type quarry was extremely remote and that the skull material belonged not to Gilmoreosaurus but Bactrosaurus. The reasoning for the paradoxical nature of the anatomy was that Bactrosaurus was not a lambeosaur or even hadrosaurid at all but instead a more primitive form of hadrosauroid merely convergent with its later relatives. They remarked that it would be informative to test the phylogenetic affinities of Gilmoreosaurus as well, but that it was too poorly described to allow this. Modern review of the species was considered to be direly needed. Seeking to finally resolve the longstanding issue, Albert Prieto-Márquez and Mark A. Norrel began work on a thorough redescription of Gilmoreosaurus; this was published in 2010. Resolving its phylogenetic position was a priority and the ultimate motive behind the endeavor. All known material of the genus was examined for the study. One thing allowed by the redescription