| Udurchukan Formation | |
| Period: | Maastrichtian |
| Age: | Maastrichtian ~ |
| Type: | Geological formation |
| Prilithology: | Conglomerate, mudstone, diamictite |
| Otherlithology: | Sandstone |
| Unitof: | Tsagayan Group |
| Underlies: | Bureya Formation |
| Overlies: | Kundur Formation |
| Thickness: | 11m (36feet) exposed at Kundur locality |
| Coordinates: | 49.5°N 129.5°W |
| Paleocoordinates: | 51.4°N 115.8°W |
| Extent: | Zeya-Bureya Basin |
The Udurchukan Formation is a geological formation located in Amur Region, Far East Russia. Based on palynomorphs such as Wodehouseia spinata, the Udurchukan is considered of Maastrichtian age of the Late Cretaceous, during the Cretaceous Period.
Since Wodehouseia spinata and Aquillapollenites subtilis are known in the Americas only from the Late Maastrichtian, the presence of these palynomorphs in the Udurchukan caused Godefroit to consider the unit and its lambeosaur dominated fauna to be coeval with the Lance Formation and Hell Creek Formation. However, research in the Songliao Basin indicates Wodehouseia spinata is also known from the early (albeit not basal) and middle Maastrichtian of Asia.
The latest view, appearing in the paper on comparative osteology of Edmontosaurus and Shantungosaurus, is that one Udurchukan Formation locality, Kundur, is late−early Maastrichtian; and the other, Blagoveschensk, is early−late Maastrichtian. The Udurchukan Formation now appears somewhat older than the Lance and Hell Creek, albeit not by much.
| Hadrosaurs reported from the Udurchukan Formation | ||||||
|---|---|---|---|---|---|---|
| Taxon | Species | Location | Stratigraphic position | Material | Notes | Images |
| Amurosaurus | A. riabinini | Blagoveschensk | A partial remnants of skull and lower jaw. | A lambeosaurine hadrosaur which was the most common dinosaur in the area, a bonebed containing many specimens was unearthed in 2008.[1] | ||
| Kerberosaurus | K. manakini | Blagoveschensk | The caudal part of cranium consists of a braincase. | A saurolophine hadrosaur | ||
| Kundurosaurus | K. nagornyi | Kundur | A partial, disarticulated skull. | A saurolophine hadrosaur; possibly synonymous with Kerberosaurus | ||
| Hadrosaurinae | Indetermidate | |||||
| Olorotitan | O. arharensis | Kundur | A nearly complete skeleton. | A hadrosaur | ||
| Sauropods reported from the Udurchukan Formation | |||||||
|---|---|---|---|---|---|---|---|
| Taxon | Species | Location | Stratigraphic position | Material | Notes | Images | |
| Arkharavia[2] | A. heterocoelica | Kundur | Upper | A single tooth and a proximal tail vertebrae, although some remains probably belong to a hadrosaurid. | A Somphospondyli sauropod.[3] | ||
| Opisthocoelicaudiinae | Indetermidate. | ||||||
| Titanosauria | Indetermidate | ||||||
| Theropods reported from the Udurchukan Formation | |||||||
|---|---|---|---|---|---|---|---|
| Taxon | Species | Location | Stratigraphic position | Material | Notes | Images | |
| Indetermidate | |||||||
| Indetermidate. | |||||||
| Indeterminate. | |||||||
| Ornithomimidae[4] | Indetermidate. | ||||||
| Richardoestesia | R. sp | ||||||
| Saurornitholestes | S. cf. sp. | ||||||
| Theropoda | Indeterminate | ||||||
| Troodon | T. sp. | ||||||
| Indetermidate. | |||||||