Udurchukan Formation

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.

Udurchukan Formation
Stratigraphic range: Maastrichtian ~70–66 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Type	Geological formation
Unit of	Tsagayan Group
Underlies	Bureya Formation
Overlies	Kundur Formation
Thickness	11 metres (40 ft) exposed at Kundur locality
Lithology
Primary	Conglomerate, mudstone, diamictite
Other	Sandstone
Location
Coordinates	49.5°N 129.5°E / 49.5; 129.5
Approximate paleocoordinates	51.4°N 115.8°E / 51.4; 115.8
Region	Amur Oblast
Country	Russia
Extent	Zeya-Bureya Basin
Udurchukan Formation (Russia)

Fossil record

Dinosaurs of Udurchukan Formation

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.

Dinosaurs

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Ornithischians

Ankylosaurs

Ankylosaurs reported from the Udurchukan Formation
Taxon	Species	Location	Stratigraphic position	Material	Notes	Images
Nodosauridae[1]	indet.	Kundur	Upper	A tooth, an incomplete tooth and an osteo dermal scute.	An indeterminate nodosauridae.

Hadrosaurs

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.[2]
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

Sauropods reported from the Udurchukan Formation
Taxon	Species	Location	Stratigraphic position	Material	Notes	Images
Arkharavia[3]	A. heterocoelica	Kundur	Upper	A single tooth and a proximal tail vertebrae, although some remains probably belong to a hadrosaurid.	A Somphospondyli sauropod.[4]
Opisthocoelicaudiinae	Indetermidate.
Titanosauria	Indetermidate

Theropods

Theropods reported from the Udurchukan Formation
Taxon	Species	Location	Stratigraphic position	Material	Notes	Images
Albertosaurinae	Indetermidate
Dromaeosaurinae	Indetermidate.
	Indeterminate.
Ornithomimidae[5]	Indetermidate.				Described as being very similar to Qiupalong[5]
Richardoestesia	R. sp
Saurornitholestes	S. cf. sp.
Theropoda	Indeterminate
Troodon	T. sp.
Tyrannosaurinae	Indetermidate.

Other fossils

Reptiles

• Amuremys planicostata
• Shamosuchus sp.
• Cimolodonta indet.
• Crocodylia indet.
• Lindholmemydidae indet.
• Testudines indet.
• Trionychidae indet.

Insects

• Mesosigara kryshtofovichi

Flora

• Cupressinoxylon sp.

See also

• Geology of Russia
• Fossils of Russia