Olorotitan

''Olorotitan'' was a genus of lambeosaurine duckbilled dinosaur from the middle or latest Maastrichtian-age Late Cretaceous, whose remains were found in the Udurchukan Formation beds of Kundur, Amur River Region, Far Eastern Russia. The type, and only species is ''Olorotitan arharensis.'' It was one of the last non-avian dinosaurs and it went extinct during the Cretaceous–Paleogene extinction event.

Discovery and naming

The holotype specimen of ''Olorotitan'', consisting of a nearly complete skeleton, was discovered in field work in the Udurchukan Formation of Kundur in the Amur region of Russia between 1999 and 2001. Pascal Godefroit and colleagues described and named it as a new species in 2003. It was the first nearly complete dinosaur specimen to be described from Russia, and is the most complete lambeosaurine skeleton discovered anywhere outside of western North America.

Large numbers of fragmentary dinosaur, turtle, and crocodilian specimens were found in the several hundred square metre area around the discovery site. Similarly aged localities in Blagoveschensk, also from the Udurchukan Formation and Jiayin, on the Chinese side of the Amur River, have yielded similarly high numbers of lambeosaurine fossils.

The generic name ''Olorotitan'' means "titanic swan" because its neck is longer when compared with other hadrosaurs, while the specific descriptor ''arharensis'' refers to Arhara County where the fossil was found.

Description

''Olorotitan arharensis'' is based on the most complete lambeosaurine skeleton found outside North America to date. It was a large hadrosaurid, comparable with other large lambeosaurines such as ''Parasaurolophus cyrtocristatus'', and may have grown up to in length, up to in height and within the range of in body mass.

It is characterized by the large hatchet-like hollow crest adorning its skull, very distinct from the crests of all of its North American relatives. The skull itself was supported by a rather elongated neck, having eighteen vertebrae, exceeding the previous hadrosaurid maximum of fifteen. The sacrum, with 15 or 16 vertebrae, has at least 3 more vertebrae than other hadrosaurids. Further along the vertebral series, in the proximal third of the tail, there are articulations between the tips of the neural spines, making that caudal area particularly rigid; the regularity of these connections suggests that they are not due to a pathology, although more specimens are needed to be certain. Godefroit and his coauthors found through a phylogenetic analysis that it was closest to ''Corythosaurus'' and ''Hypacrosaurus''.

Palaeobiology

As a hadrosaurid, ''Olorotitan'' would have been a bipedal/quadrupedal herbivore, eating plants with a sophisticated skull that permitted a grinding motion analogous to chewing, and was furnished with hundreds of continually-replaced teeth. Its tall, broad hollow crest, formed out of expanded skull bones containing the nasal passages, probably functioned in identification by sight and sound.

Palaeoecology

''O. arharensis'' shared its time and place with several other types of animal, including two other lambeosaurines: the ''Parasaurolophus''-like ''Charonosaurus'' and more basal ''Amurosaurus''. Additionally, remains from turtles, crocodilians, theropods, and nodosaurids were found at its discovery site, and the ''Saurolophus''-like hadrosaurine '' Kerberosaurus'' is also known from roughly contemporaneous rocks in the area. Unlike the situation in North America, where lambeosaurines are virtually absent from Late Maastrichtian rocks, Asian lambeosaurines are diverse and common at the end of the Mesozoic, suggesting climatic or ecological differences.

See also

* Timeline of hadrosaur research

References

{{Taxonbar, from=Q132470

Lambeosaurines
Late Cretaceous dinosaurs of Asia
Maastrichtian life
Fossil taxa described in 2003
Taxa named by Pascal Godefroit
Maastrichtian genus first appearances
Maastrichtian genus extinctions
Ornithischian genera