Olorotitan

Olorotitan arharensis was a large lambeosaurine dinosaur belonging to the monotypic genus Olorotitan, which lived during the late Maastrichtian period of the Late Cretaceous era. It was among the last non-avian dinosaurs to become extinct and is known from nearly complete remains discovered in the Udurchukan Formation near Kundur, Amur Oblast, Eastern Russia. The holotype specimen, described by Pascal Godefroit and colleagues in 2003, represents the most complete lambeosaurine skeleton found outside of western North America.

The generic name "Olorotitan" translates to "titanic swan," reflecting its long neck compared to other hadrosaurs. The specific descriptor "arharensis" refers to Arhara County, where the fossil was discovered. Olorotitan was a large herbivore, reaching up to 8 meters in length, 3.5 meters in height, and weighing between 2.6–3.4 metric tons. It had a distinctive hollow crest on its skull, which likely served for visual and auditory recognition.

The species is characterized by an elongated neck with eighteen vertebrae, a sacrum with additional vertebrae compared to other hadrosaurids, and rigid articulations in the tail region. Phylogenetic analyses suggest it was closely related to Corythosaurus and Hypacrosaurus. Olorotitan shared its habitat with other dinosaurs, including Charonosaurus and Amurosaurus, as well as turtles, crocodilians, theropods, and nodosaurids. Unlike North America, lambeosaurines were diverse in Asia during the Late Maastrichtian, indicating possible ecological or climatic differences.

The discovery of Olorotitan arharensis provides significant insights into the paleobiology and distribution of hadrosaurine dinosaurs at the end of the Mesozoic era.