Amurosaurus

Phylogeny: Dinosauria > Ornithischia > Genasauria > Neornithischia > Cerapoda > Ornithopoda > Iguanodontia > Ankylopollexia > Styracosterna > Hadrosauriformes > Hadrosauroidea > Hadrosauridae > Lambeosaurinae

Overview: Amurosaurus takes its name from the Amur River, also known as the Heilong River, that flows along the border of Russia’s far east and the northeast of China. Fossils of the animal were found close to the Amur, within the Late Cretaceous-aged Udurchukan Formation – on the Russian side of the river – back in the mid-1980’s. Described in 1991, Amurosaurus is only one of a number of “duck-billed” hadrosaurids known from the Udurchukan. Other notable dinosaurs from its rock layers include Olorotitan and Kerberosaurus. Amurosaurus was more closely related to the former, being a fellow member of the hadrosaurid subfamily Lambeosaurinae. Lambeosaurines usually had hollow, bony head crests. While most of its skeleton is known, the top portion of the skull remains a mystery for Amurosaurus, so we can’t know for certain it had one, but it’s highly likely.

Recovered fossils referred to this animal include a fair bit of the skull, the lower jaw, a fair number of its vertebrae, some ribs, the pelvis, and more or less all of the limbs. Amurosaurus would’ve been similar in appearance to most other hadrosaurids, being a fairly bulky herbivore that spent most of its time down on all fours, but still retained the ability to walk bipedally. The front of its mouth had a keratinous beak, with rows of tightly-packed teeth set in behind it. If it did possess a head crest, it most likely used it for courtship purposes, or possibly as a resonating chamber to make loud calls, if it was linked into its respiratory system, as was common with the crests of lambeosaurines. One of the specimens referred to Amurosaurus preserves swelling on a bone from the lower forelimb (probably causing a limp). The genus Sahaliyania, also known from the Udurchukan, is possibly a junior synonym of Amurosaurus.