Udurchukan Formation

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°30′N 129°30′E / 49.5°N 129.5°E / 49.5; 129.5
Approximate paleocoordinates	51°24′N 115°48′E / 51.4°N 115.8°E / 51.4; 115.8
Region	Amur Oblast
Country	Russia
Extent	Zeya-Bureya Basin
Udurchukan Formation (Russia) Show map of Russia Udurchukan Formation (Amur Oblast) Show map of Amur Oblast

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.

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.

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.				Similar in size to Tyrannosaurus[6]

Reptiles

Reptiles reported from the Udurchukan Formation
Taxon	Species	Location	Stratigraphic position	Material	Notes	Images
Amuremys	A. planicostata
Cimolodonta	indet.
Crocodylia	indet.
Lindholmemydidae	indet.
Shamosuchus	S. sp.
Testudines	indet.
Trionychidae	indet.

Insects

Plants reported from the Udurchukan Formation
Taxon	Species	Location	Stratigraphic position	Material	Notes	Images
Mesosigara	M. kryshtofovichi

Flora

Plants reported from the Udurchukan Formation
Taxon	Species	Location	Stratigraphic position	Material	Notes	Images
Cupressinoxylon	C. sp.

See also

• Geology of Russia
• Fossils of Russia

References

1. Tumanova, Tatiana & Bolotsky, Yu.L. & Alifanov, Vladimir. (2004). The first finds of armored dinosaurs in the Upper Cretaceous of Russia (Amur Region). Paleontological Journal. 38. 73-77.
2. Lauters, Pascaline; Bolotsky, Yuri L.; Van Itterbeeck, Jimmy; Godefroit, Pascal (March 1, 2008). "Taphonomy and Age Profile of a Latest Cretaceous Dinosaur Bone Bed in Far Eastern Russia". PALAIOS. 23 (3). SEPM Society for Sedimentary Geology: 153–162. Bibcode:2008Palai..23..153L. doi:10.2110/palo.2006.p06-031r. Retrieved 1 May 2021.
3. Alifanov, Vladimir & Bolotsky, Yu. (2010). Arkharavia heterocoelica gen. et sp. nov., a new sauropod dinosaur from the Upper Cretaceous of the Far East of Russia. Paleontological Journal. 44. 84-91. 10.1134/S0031030110010119.
4. Mannion, Philip D.; Upchurch, Paul; Barnes, Rosie N.; Mateus, Octávio (2013). "Osteology of the Late Jurassic Portuguese sauropod dinosaur Lusotitan atalaiensis (Macronaria) and the evolutionary history of basal titanosauriforms". Zoological Journal of the Linnean Society. 168: 98–206. doi:10.1111/zoj.12029.
5. Averianov, Alexander; Skutschas, Pavel; Bolotsky, Yuriy; Bolotsky, Ivan (2023-12-31). "First find of an ornithomimid theropod dinosaur in the Upper Cretaceous of the Russian Far East". Biological Communications. 68 (4). doi:10.21638/spbu03.2023.405. ISSN 2587-5779.
6. Yun, Changyu. "Testing the hypotheses of the origin of Tyrannosaurus rex: immigrant species, or native species?" (PDF). The Journal of Paleontological Sciences: 1–9.

Bibliography

• Y. A. Popov. 1971. Historical development of the infraorder Nepomorpha (Heteroptera). Akademiya Nauk SSSR, Trudy Paleontologicheskogo Instituta 129:1-228