Ilek Formation

The Ilek Formation is a Lower Cretaceous geologic formation in Western Siberia. Many different fossils have been recovered from the formation. It overlies the Late Jurassic Tyazhin Formation and underlies the Albian Kiya Formation.[1]

Ilek Formation
Stratigraphic range: Lower Cretaceous
TypeGeological formation
Unit ofKiya River Basin
UnderliesKiya Formation
OverliesTyazhin Formation
ThicknessUp to 746 metres (2,450 ft)
Lithology
PrimaryClay, siltstone
OtherMarl, sandstone
Location
Coordinates55.9°N 88.0°E / 55.9; 88.0
Approximate paleocoordinates54.2°N 84.6°E / 54.2; 84.6
RegionWestern Siberia
Country Russia
Extent Kemerovo Oblast
Type section
Named byL. A. Ragozin
Year defined1935
Ilek Formation (Russia)
Ilek Formation (Kemerovo Oblast)

The formation was described by L. A. Ragozin in 1935. It consists of sands with sandstone concretions, layers of silts, clays and marls.[2] Age of the formation, according to a crude 1962 estimate, is Valanginian(?) - Hauterivian - Barremian. Its thickness varies greatly, reaching 746 m in Teguldet borehole.[3]

Fauna
Dinosaurs reported from the Ilek Formation
Genus Species Location Stratigraphic position Material Notes Images
Evgenavis[4] E. nobilis Siberia A set of limb elements A confuciusornithiform
Mystiornis[5] M. cyrili Western Siberia Shestakovo-1 locality Isolated metatarsus An avisaurid enantiornithean
Psittacosaurus[6] P. sibiricus Western Siberia Shestakovo Several skeletons A ceratopsian
Sibirotitan[7] S. astrosacralis Western Siberia Vertebrae, sacrum, and previously published pedal elements A somphospondylan
Dromaeosauridae[8] Indeterminate Teeth
Lithostrotia indet.[9] Indeterminate Western Siberia Caudal vertebrae A titanosaur
?Tyrannosauroidea Indeterminate Teeth
Turtles reported from the Ilek Formation
Genus Species Location Stratigraphic position Material Notes Images
Kirgizemys Indeterminate A macrobaenid
Crocodylomorphs reported from the Ilek Formation
Genus Species Location Stratigraphic position Material Notes Images
Kyasuchus[10] K. saevi Siberia A partial skull A shartegosuchid crocodyliform
Tagarosuchus[11] T. kulemzini Southern Siberia Shestakovo Nearly complete skull A crocodyliform
Mammaliamorphs reported from the Ilek Formation
Genus Species Location Stratigraphic position Material Notes Images
Acinacodus[12] A. tagaricus Western Siberia Right dentary fragment An amphidontid mammal
Baidabatyr[13] B. clivosus Siberia Bol'shoi Kemchug 3 locality Upper premolar A multituberculate

Gobiconodon

G. hoburensis[14]

Siberia

 21 upper and lower jaws. A gobiconodont

G. borissiaki[15]

 Siberia A fragmentary lower jaw A gobiconodont
Kemchugia[16] K. magna A tooth An amphilestid mammal
Kiyatherium[17] K. cardiodens Western Siberia A maxilla A zhangheotheriid mammal
Sibirotherium[18] S. rossicus Siberia Lower jaw fragments A docodont mammaliaform
Xenocretosuchus[19] X. sibiricus Siberia Dental elements A tritylodontid mammaliamorph
Yermakia[16] Y. domitor Siberia Shestakovo-1 locality A mandible A tinodontid mammal
Amphibians reported from the Ilek Formation
Genus Species Location Stratigraphic position Material Notes Images
Kiyatriton K. leshchinskiyi Western Siberia A set of vertebrae A salamander
Lizards reported from the Ilek Formation
Genus Species Location Stratigraphic position Material Notes Images
Ilekia[20] I. sibirica Western Siberia Bol'shoi Kemchug 3 locality A member of Paramacellodidae
Shestakovia S. voronkevichi Western Siberia Bol'shoi Kemchug 3 locality A knob-scaled lizard

See also

References
  1. Golovneva, L. B.; Shchepetov, S. V. (April 2010). "Phytostratigraphy of Albian-Cenomanian sediments in the Kiya River basin (the Chulym-Yenisei area of the west Siberian lowland)". Stratigraphy and Geological Correlation. 18 (2): 153–165. doi:10.1134/s0869593810020048. ISSN 0869-5938.
  2. Криштофович А. Н., ed. (1955). "Илекская свита". Геологический словарь. 1 (А-Л). p. 271.
  3. Лебедев И. В., ed. (1962). Биостратиграфия мезозойских и третичных отложений Западной Сибири. pp. 168–169.
  4. O'Connor, JL; Averianov, AO; Zelenkov, NV (2014). "A confuciusornithiform (Aves, Pygostylia)-like tarsometatarsus from the Early Cretaceous of Siberia and a discussion of the evolution of avian hind". Journal of Vertebrate Paleontology. 34 (3): 647–656. doi:10.1080/02724634.2013.828734.
  5. Evgeny N. Kurochkin; Nikita V. Zelenkov; Alexandr O. Averianov; Sergei V. Leshchinskiy (2011). "A new taxon of birds (Aves) from the Early Cretaceous of Western Siberia, Russia". Journal of Systematic Palaeontology. 9 (1): 109–117. doi:10.1080/14772019.2010.522202.
  6. Averianov, Alexander O.; Voronkevich, Alexei V.; Leshchinskiy, Sergei V.; Fayngertz, Alexei V. (2006). "A ceratopsian dinosaur Psittacosaurus sibiricus from the Early Cretaceous of West Siberia, Russia and its phylogenetic relationships". Journal of Systematic Palaeontology. 4 (4): 359–395. doi:10.1017/s1477201906001933.
  7. Alexander Averianov; Stepan Ivantsov; Pavel Skutschas; Alexey Faingertz; Sergey Leshchinskiy (2018). "A new sauropod dinosaur from the Lower Cretaceous Ilek Formation, Western Siberia, Russia". Geobios. in press. doi:10.1016/j.geobios.2017.12.004.
  8. Averianov, A.O.; Ivantsov, S.V.; Skutschas, P.P. (2019-06-25). "Theropod teeth from the Lower Cretaceous Ilek Formation of Western Siberia, Russia". Proceedings of the Zoological Institute of the Russian Academy of Sciences (in Russian). 323 (2): 65–84. doi:10.31610/trudyzin/2019.323.2.65. ISSN 0206-0477.
  9. Alexander O. Averianov; Stepan V. Ivantsov; Pavel P. Skutschas (2020). "Caudal vertebrae of titanosaurian sauropod dinosaurs from the Lower Cretaceous Ilek Formation in Western Siberia, Russia". Cretaceous Research. 107: Article 104309. doi:10.1016/j.cretres.2019.104309.
  10. Efimov, M. B. and Leshchinskiy, S. V. (2000). First finding of the fossil crocodile skull in Siberia [in Russian]. In: Komarov, A. V., ed., Materialy regional’noj konferencii geologov Sibiri, Dal’nego Vostoka i Severo−Vostoka Rossii. Tom II, 361–363. GalaPress, Tomsk.
  11. Fiorelli, L.E.; Calvo, J.O. (2007). "The first "protosuchian" (Archosauria: Crocodyliformes) from the Cretaceous (Santonian) of Gondwana" (PDF).
  12. A. V. Lopatin; E. N. Maschenko & A. O. Averianov (2010). "A new genus of triconodont mammals from the Early Cretaceous of Western Siberia". Doklady Biological Sciences. 433 (1): 282–285. doi:10.1134/S0012496610040137.
  13. Alexander Averianov; Alexey Lopatin; Pavel Skutschas; Stepan Ivantsov; Elizaveta Boitsova; Ivan Kuzmin (2017). "An enigmatic multituberculate mammal from the Early Cretaceous of Siberia, Russia". Journal of Vertebrate Paleontology. 37 (2): e1293070. doi:10.1080/02724634.2017.1293070.
  14. Trofimov, B. A. (1978). "The first triconodonts (Mammalia, Triconodonta) from Mongolia". Doklady Akademii Nauk SSSR. 243 (1): 213–216.
  15. Maschenko, E. N.; Lopatin, A. V. (1998). "First record of an Early Cretaceous triconodont mammal in Siberia". Bull. Inst. R. Sci. Nat. Belg. 68: 233–236.
  16. A. V. Lopatin, E. N. Maschenko, A. O. Averianov, A. S. Rezvyi, P. P. Skutschas and S. V. Leschinskiy. 2005. Early Cretaceous Mammals from Western Siberia: 1. Tinodontidae. Paleontological Journal 39(5):523-534
  17. E. N. Maschenko and A. V. Lopatin. 2002. A new Early Cretaceous mammal from Western Siberia. Doklady Biological Sciences 386:475-477
  18. http://zmmu.msu.ru/rjt/articles/article.php?volume=1&issue=2&pages=75-81
  19. http://fossilworks.org/cgi-bin/bridge.pl?a=taxonInfo&taxon_no=254183
  20. A. O. Averianov, P. P. Skutschas, A. V. Lopatin, S. V. Leschinskiy, A. S. Rezvyi and A. V. Fayngerts. 2005. Early Cretaceous mammals from Bol'shoi Kemchug 3 locality in West Siberia, Russia. Russian Journal of Theriology 4(1):1-12
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