Jaxartosaurus

Discovery

The first dinosaurs in Kazakhstan were discovered in 1923, brought from the South Kazakhstan region and interpreted by Soviet palaeontologist Anatoly Riabinin as hadrosaurid and theropod remains. The dinosaur horizon lay within a red limestone layer beneath a calcareous red sandstone containing abundant petrified wood. Higher up, dinosaur bones and teeth were more fragmentary, and Riabinin interpreted the entire deposit as Cenomanian in age. From 1924 to 1926, geologist Vasilij Prynada excavated the horizon near Tashkent, finding the most abundant fossils along a 20 km stretch of the Alymtau Range near the Kyrk-Kuduk well.

Riabinin informally proposed the names 'Jaxartosaurus aralensis' and 'Bactrosaurus prynadai' in 1937 and 1938, then formally described both in 1939. The genus name derives from the ancient name of the Syr Darya, 'Yaxart', and the species name refers to the nearby Aral Sea. Riabinin considered much of the hadrosaurid skeletal material as possibly from a single individual, the syntype collection PIN No. 5009, including parts of the skull, forelimb, and hindlimb.

Based on the skull roof, he classified Jaxartosaurus as a member of Lambeosaurinae, only the second from Asia after Bactrosaurus.