Bactrosaurus
Bactrosaurus johnsoni in the Hong Kong Science Museum
- Asia: Inner Mongolia, People's Republic of China
- Bactrosaurus johnsoni
- Bactrosaurus kysylkumensis
Bactrosaurus was a genus of dinosaur bird Beck from the group of Hadrosauridae. Fossil record of this genus are from the Late Cretaceous ( Campanian ). The fossils of the type species B. johnsoni were found in the Gobi Desert in Inner Mongolia and described in 1933.
Features
Bactrosaurus reached a body length of four to six meters and weigh two tonnes.
By B. johnsoni are single bones, as well as complete skull present during known by B. kysylkumensis few thoracic vertebrae, an upper jaw and individual teeth of at least six nearly complete skeletons of different ages.
Localities
The first fossils of B. johnsoni were found in 1933 in the Irish - Dabasu formation near the town Eren Hot in Inner Mongolia, People's Republic of China in the Gobi Desert. In 1921 were discovered by the American paleontologist Roy Chapman Andrews in this rich archaeological site first dinosaur remains.
In the Irish - Dabasu lineup a number of other dinosaur skeletons have been discovered in various excavations, including the theropods Alectrosaurus olseni and Archaeornithomimus asiaticus and Gilmoreosaurus mongoliensis another early representatives of the hadrosaur. In the nearby Minhe formation, which is also assigned to the Upper Cretaceous, there were more species, including the Velociraptor mongoliensis ( theropods ) which Protoceratopsiden Microceratops gobiensis and Protoceratops andrewsi and the remains unallocated theropods and sauropods.
System
Bactrosaurus is regarded as the representative of the subfamily Lambeosaurinae and filed there in the close relationship of the genera Parasaurolophus, Lambeosaurus, Corythosaurus and Hypacrosaurus. This relationship is justified due to various skull and bone characteristics, including by modified nasal cavities, the expression of the temporomandibular joint, the formation of the teeth, elongated spinous processes, pelvic training. Together with Prosaurolophus he is the most primitive representatives of Lambeosaurinae, as these no so pronounced nasal cavities possess such advanced types. Because of another skeleton discovery in 1998, this classification was resolved because Bactrosaurus had no forehead comb before the eyes.
Alternatively Bactrosaurus is probably an early hadrosaur from the relationship of Gilmoreosaurus in what other way he would include in the relationship among the genera Claosaurus, Tanius and Secernosaurus, but a more accurate assignment it is currently due to the scanty material is not present.
The type species B. johnsoni was first discovered in 1933 by Charles W. Gilmore and described together with a number of other dinosaurs. In addition to the type species of the genus also B. 1937 newly described by Anatoly Riabinin as Cionodon kysylkumensis first described in 1995 by Lev Alexandrovich Nessov as part of a comprehensive revision of the Russian dinosaur discoveries is slammed kysylkumensis.
The example also described by Riabinin prynadai shall be considered together with Tanius prynadai as a noun dubium.