Open Paleo

Jaxartosaurus

Riabinin, 1937 jak-SAHR-to-SAWR-us

Named after the Jaxartes (ancient Greek name for the Syr Darya river in Kazakhstan); meaning "Jaxartes lizard"

89.8–83.6 million years ago Coniacian–Santonian, Late Cretaceous
Late Cretaceous stages

Jaxartosaurus is a genus of hadrosaurid dinosaur similar to Corythosaurus which lived during the Late Cretaceous. Its fossils were found in Kazakhstan.

Diagnosis

  1. Anterior end of the dentary strongly drawn downward, bearing a rounded projection along its anterior edge, unlike other lambeosaurines
  2. Dentary bearing 34–35 tooth rows
  3. Ischium with a closed, oval obturator foramen (round in Hypacrosaurus)
  4. Humerus with a narrow, non-expanded proximal end, unlike Mandschurosaurus or Tanius

Species

Jaxartosaurus aralensis Riabinin, 1937

Type species

Named for the Aral Sea, near the discovery locality in Kazakhstan.

Lectotype
CCMGE 1/5009 , F.N. Chernyshev Central Museum of Geological Exploration
Material
Incomplete skull lacking the snout.
Notes
Riabinin (1939) founded the species on a series from collection 5009: the posterior part of a skull, a dentary, a surangular, vertebrae and limb bones. Rozhdestvensky (1968) designated the skull, No. 1/5009, at the museum of the Central Science and Research Institute for Geological Exploration in Leningrad, as the lectotype. Bell and Brink (2013) write it as PIN 1/5009 and report the other elements lost.
Horizon
Syuksyuk Formation, Coniacian–Santonian, Late Cretaceous , 89.8–83.6 million years ago
Locality
Kyrkkuduk I, Turkistan, Kazakhstan

References

  1. Rozhdestvensky, A. K. (1968). Gadrozavry Kazakhstana [Hadrosaurs of Kazakhstan]. [Upper Paleozoic and Mesozoic Amphibians and Reptiles]. Akademia Naul SSSR, Moscow 97-141.

    Designates the skull No. 1/5009 as the lectotype, at "The Museum of the Central Science and Research Institute for Geological Exploration (Leningrad)".

    rozhdestvensky1968a
  2. Bell, P. R.; Brink, K. S. (2013). Kazaklambia convincens comb. nov., a primitive juvenile lambeosaurine from the Santonian of Kazakhstan. Cretaceous Research 45: 265-274. Elsevier BV. doi:10.1016/j.cretres.2013.05.003

    Gives the specimen as PIN 1/5009, of which "Only the skull is currently available for study".

    bell2013a
  3. Riabinin, A. N. (1937). O nakhodke shlemonosnykh form Dinosauria verkhnemelovykh otlozheniyakh yuzhnogo Kazakhstana [The discovery of crested forms of Upper Cretaceous dinosaurs in southern Kazakhstan]. Priroda 1937(9): 91. riabinin1937a
  4. Riabinin, A. N. (1939). Fauna pozvonochnykh iz verkhnego mela yuzhnogo Kazakhstana. I. Reptilia. Chast' 1. 1. Ornithischia [The Upper Cretaceous vertebrate fauna of South Kazakhstan. I. Reptilia. Part 1. 1. Ornithischia]. Transactions of the Central Geological and Prospecting Institute 118: 1-39. riabinin1939a
  5. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Ornithischians. Princeton University Press.

    Source of the appearance features.

    jones2026a
  6. Nessov, L. A. (1995). Dinozavri severnoi Yevrazii: Novye dannye o sostave kompleksov, ekologii i paleobiogeografii [Dinosaurs of northern Eurasia: new data about assemblages, ecology, and paleobiogeography]. Institute for Scientific Research on the Earth's Crust, St. Petersburg State University, St. Petersburg 1-156.

    Gives the locality for Jaxartosaurus as Kyrkkuduk I, and the formation as the Syuksyuk.

    nessov1995a