Gilmoreosaurus (meaning "Charles Whitney Gilmore's lizard") is the name given to a genus of dinosaur from the Cretaceous of Asia. The type species is Gilmoreosaurus mongoliensis. It is believed to be a hadrosaur or iguanodont from the Iren Dabasu Formation of Inner Mongolia, dating to 96 Ma ago. Additional specimens have been described as distinct species, including G. atavus from the Khodzhakul Formation of Uzbekistan (120 Ma ago) and G. arkhangelskyi from the Bissekty Formation (89 Ma ago). However, these are based on very fragmentary remains, and their classification is dubious. An additional species, G. kysylkumense (also from the Bissekty Formation) is sometimes included, though it has also been referred to the related genus Bactrosaurus. History of study Asian expeditions and Gilmore's "Mandschurosaurus mongoliensis" In the early twentieth century, the American Museum of Natural History (AMNH) conducted a series of palaeontological expeditions to the deserts of Asia. One geologic formation where work was conducted during these expeditions was the Iren Dabasu Formation in Inner Mongolia, China. The fieldwork here was done by a field team led by Walter Granger. Nobody among them were specialists in dinosaurs; instead the AMNH had sent mostly geologists and mammal palaeontologists. Many dinosaur remains were discovered, but their nature would remain unknown to the discovers until experts back in America examined the material. The initial excavations of dinosaur fossils at Iren Dabasu took place on three days in April and May 1922. They conducted more extensive digs a year later from April 23 to June 1, 1923. Several new genera and species were discovered from the formation; among them were two new types of hadrosaur. It was these two that would later prove to be the most significant of the finds. They were among the first remains of the group from the continent, preceded only by Mandschurosaurus amurensis, Tanius sinensis, some remains from Turkestan and Saurolophus krischtofovici, with the validity of the latter species already doubted. The material that would eventually come to be known as Gilmoreosaurus was discovered by George Olsen (a member of Granger's team) in two different quarries (145 and 149, about apart), around northeast of the town of Erenhot and not far from the border with Mongolia. Several individuals were represented and between them most of the skeleton found, but the material was disarticulated and so what pieces belonged to each individual is not possible to determine for certain. Once it