Ilek Formation

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Ilek Formation
Stratigraphic range: Lower Cretaceous,
Barremian–Aptian
Shestakovo-3.jpg
Shestakovo 3 locality
Type Geological formation
Unit of Kiya River Basin
Underlies Kiya Formation
Overlies Tyazhin Formation
ThicknessUp to 746 metres (2,450 ft)
Lithology
Primary Clay, siltstone
Other Marl, sandstone
Location
Coordinates 55°54′N88°00′E / 55.9°N 88.0°E / 55.9; 88.0
Approximate paleocoordinates 54°12′N84°36′E / 54.2°N 84.6°E / 54.2; 84.6
RegionWestern Siberia
CountryFlag of Russia.svg  Russia
ExtentFlag of Kemerovo Oblast.svg  Kemerovo Oblast
Type section
Named byL. A. Ragozin
Year defined1935
Russia rel location map.png
Green pog.svg
Ilek Formation (Russia)
Relief Map of Kemerovo Oblast.jpg
Green pog.svg
Ilek Formation (Kemerovo Oblast)

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]

Contents

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] A more recent 2024 estimate based on invertebrate and vertebrate fossils placed the age of the formation at Barremian–Aptian. [4]

Age

View of Shestakovo 1 outcrops (upper left corner) from the Kiya River Shestakovskii iar.jpg
View of Shestakovo 1 outcrops (upper left corner) from the Kiya River

The Ilek Formation conformably overlies the Upper Jurassic Tyazhin Formation. [1] Gastropods and bivalves of Valanginian age have been recovered from the lower part of the formation, and gastropods and bivalves of Hauterivian to Barremian age have been found in the upper part, as well as Barremian ostracods. The age of the Shestakovo 1 locality is poorly constrained. [5] Palynological samples from the Shestakovo 3 locality are characteristic of the Aptian. No angiosperm pollen has been found at this locality, indicating that it is older than the Albian. [6] The upper layers of the formation do contain angiosperm pollen, indicating that part of the formation may extend into the Albian. The overlying Kiya Formation is upper Albian based on plant biostratigraphy. [1]

Fauna

Amphibians

Amphibians reported from the Ilek Formation
TaxonLocalityMaterialNotesImages
Kiyatriton leshchinskiyi [7]
  • Shestakovo 1
 Atlas, trunk vertebrae, fragmentary dentaries, femora, humerus, and nearly complete iliumA crown-group salamander
Kuzbassia sola [8]
  • Shestakovo 1
Two atlantal centra and a trunk vertebral centrumA karaurid

Mammaliamorphs

Mammaliamorphs reported from the Ilek Formation
TaxonLocalityMaterialNotesImages
Acinacodus tagaricus [9] Right dentary fragmentAn amphidontid mammal
Baidabatyr clivosus [10]
  • Bol'shoi Kemchug 3
Upper premolarA multituberculate
Gobiconodon hoburensis [11] 21 upper and lower jaws.A gobiconodont
Gobiconodon borissiaki [12] A fragmentary lower jawA gobiconodont
Kemchugia magna [13] A toothAn amphilestid mammal
Kiyatherium cardiodens [14] A maxillaA zhangheotheriid mammal
Xenocretosuchus sibiricus [15] Dental elementsA tritylodontid mammaliamorph
Yermakia domitor [13]
  • Shestakovo 1
A mandibleA tinodontid mammal
Sibirotherium rossicum [16]
  • Bol'shoi Kemchug 4
M1 tooth; [16] mandibular fragments [17] A docodontan mammaliaform

Choristoderes

Choristoderes reported from the Ilek Formation
TaxonLocalityMaterialNotesImages
cf. Khurendukhosaurus [18]
  • Bol'shoi Kemchug 3
Dorsal vertebra, sacral vertebraA non-neochoristodere choristodere
"Shestakovo choristodere" [18]
  • Shestakovo
  • Bol'shoi Kemchug 3
  • Bol'shaya Terekhtul' 2
Fragmentary dentaries, several vertebrae, rib fragmentsA possible neochoristodere
Choristodera indet. [18]
  • Smolenskii Yar
Cervical centrumMay represent a taxon distinct from both Khurendukhosaurus and the Shestakovo choristodere

Lizards

Lizards reported from the Ilek Formation
TaxonLocalityMaterialNotesImages
Paramacellodidae indet. [4] [19] ("Ilekia sibirica" [13] )
  • Bol'shoi Kemchug 3
Platynota indet. [4] ("cf. Parviraptor sp." [13] )
  • Bol'shoi Kemchug 3
Xenosauridae indet. [4] [19] ("Shestakovia voronkevichi" [13] )
  • Bol'shoi Kemchug 3
A knob-scaled lizard

Turtles

Turtles reported from the Ilek Formation
TaxonLocalityMaterialNotesImages
Kirgizemys A macrobaenid

Crocodylomorphs

Crocodylomorphs reported from the Ilek Formation
TaxonLocalityMaterialNotesImages
Kyasuchus saevi [20]
  • Shestakovo 3
A partial skullA shartegosuchid crocodyliform
Tagarosuchus kulemzini [21]
  • Shestakovo 3
Nearly complete skullA crocodyliform

Pterosaurs

Pterosaurs reported from the Ilek Formation
TaxonLocalityMaterialNotesImage
?Ctenochasmatidae indet. [13]
  • Bol'shoi Kemchug 3
cf. Lonchognathosaurus sp. [22]
  • Novochernorechensk
Wing metacarpal fragmentA dsungaripterid
Ornithocheiridae indet. [23]
  • Shestakovo 1
Pterodactyloidea indet. [13]
  • Bol'shoi Kemchug 3

Dinosaurs

Theropods reported from the Ilek Formation
TaxonLocalityMaterialNotesImages
Evgenavis nobilis [24] A set of limb elementsA confuciusornithiform
Evgenavis tarsometatarsus.png
Mystiornis cyrili [25]
  • Shestakovo 1
Isolated metatarsusAn avisaurid enantiornithean
Mystiornis.png
Paraves indet. [26] TeethMay belong to either Microraptorinae or Troodontidae
Theropoda indet. [27]
  • Shestakovo 1
Partial cervical vertebraA long-necked theropod, possibly similar to basal therizinosauroids like Falcarius
Tyrannosauroidea indet. [26] Teeth
cf. Urbacodon sp. [26] TeethA troodontid with unserrated teeth
Sauropodomorphs reported from the Ilek Formation
TaxonLocalityMaterialNotesImages
Lithostrotia indet. [28] Caudal vertebraePotentially three distinct taxa of titanosaur
Sibirotitan astrosacralis [5]
  • Shestakovo 1
  • Shestakovo 3 [29]
Vertebrae, sacrum, and pedal elementsA somphospondylan sauropod
Sibirotitan model.jpg
Ornithischians reported from the Ilek Formation
TaxonLocalityMaterialNotesImages
Ornithischia indet. [4]
  • Shestakovo 1
  • Bol'shoi Kemchug 3
Isolated teethOriginally identified as two distinct "hypsilophodontid" taxa [30]
Psittacosaurus sibiricus [31]
  • Shestakovo
Several skeletonsA ceratopsian
Psittacosaurus sibiricus.png
Stegosauria indet. [13]
  • Bol'shoi Kemchug 3
Isolated teeth [30]

See also

Related Research Articles

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References

  1. 1 2 3 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. Bibcode:2010SGC....18..153G. doi:10.1134/s0869593810020048. ISSN   0869-5938. S2CID   140540821.
  2. ↑ Криштофович А. Н., ed. (1955). "Илекская свита". Геологический словарь. Vol. 1 (А-Л). p. 271. ISBN   9785458366533.
  3. ↑ Лебедев И. В., ed. (1962). Биостратиграфия мезозойских и третичных отложений Западной Сибири. pp. 168–169.
  4. 1 2 3 4 5 Ivantsov, S. V.; Fayngerts, A. V.; Feofanova, O. A.; Vladimirova, O. N.; Slobodin, D. A. (2024). "Early Cretaceous continental sedimentatary environments, palaeogeography and biota of southeastern Western Siberia". Geological Society, London, Special Publications. 545. doi:10.1144/SP545-2023-62.
  5. 1 2 Averianov, Alexander; Ivantsov, Stepan; Skutschas, Pavel; Faingertz, Alexey; Leshchinskiy, Sergey (2018). "A new sauropod dinosaur from the Lower Cretaceous Ilek Formation, Western Siberia, Russia". Geobios. 51 (1): 1–14. Bibcode:2018Geobi..51....1A. doi:10.1016/j.geobios.2017.12.004. ISSN   0016-6995.
  6. ↑ Bugdaeva, E V; Markevich, V S; Volynets, E B (2017). "Palaeoenvironmental and palaeoclimatic reconstruction of the Early Cretaceous psittacosaur localities, Asia". Proceedings and Field Guidebook for the Fifth International Symposium of International Geoscience Programme IGCP Project 608. Fifth International Symposium of International Geoscience Programme. Jeju Island, Korea. pp. 31–34.
  7. ↑ Skutschas, P. P. (2014). "Kiyatriton leshchinskiyi Averianov et Voronkevich, 2001, a crown-group salamander from the Lower Cretaceous of Western Siberia, Russia". Cretaceous Research. 51: 88–94. doi:10.1016/j.cretres.2014.05.014. ISSN   0195-6671.
  8. ↑ Skutschas, P.; Kolchanov, V.; Anpilogova, E.; Parakhin, I.; Averianov, A.; Jones, M. (2023). "The last of them? A new relic karaurid stem salamander from the Lower Cretaceous of Western Siberia, Russia". Biological Communications. 68 (4): 219–226. doi:10.21638/spbu03.2023.402.
  9. ↑ 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.
  10. ↑ 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.
  11. ↑ Trofimov, B. A. (1978). "The first triconodonts (Mammalia, Triconodonta) from Mongolia". Doklady Akademii Nauk SSSR. 243 (1): 213–216.
  12. ↑ 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.
  13. 1 2 3 4 5 6 7 8 Averianov, A. O.; Skutschas, P. P.; Lopatin, A. V.; Leshchinskiy, S. V.; Rezvyi, A. S.; Fayngerts, A. V. (2005). "Early Cretaceous mammals from Bol'shoi Kemchug 3 locality in West Siberia, Russia". Russian Journal of Theriology. 4 (1): 1–12. doi: 10.15298/rusjtheriol.04.1.01 .
  14. ↑ E. N. Maschenko and A. V. Lopatin. 2002. A new Early Cretaceous mammal from Western Siberia. Doklady Biological Sciences 386:475-477
  15. ↑ "Fossilworks: Stereognathus".
  16. 1 2 Lopatin, A. V.; Averianov, A. O.; Ivantsov, S. V.; Kuzmin, I. T.; Skutschas, P. P. (2023-07-19). "An Upper Molar of a Docodontan (Docodonta, Mammaliaformes) from the Lower Cretaceous of Western Siberia". Doklady Earth Sciences. doi:10.1134/S1028334X23601128. ISSN   1028-334X.
  17. ↑ Maschenko, E. N.; Lopatin, A. V.; Voronkevich, A. V. (2002). "A new genus of the tegotheriid docodonts (Docodonta, Tegotheriidae) from the Early Cretaceous of West Siberia". Russian Journal of Theriology. 1 (2): 75–81. doi: 10.15298/rusjtheriol.01.2.01 .
  18. 1 2 3 Skutschas, Pavel P.; Vitenko, Dmitriy D. (2017-05-04). "Early Cretaceous choristoderes (Diapsida, Choristodera) from Siberia, Russia". Cretaceous Research. 77: 79–92. Bibcode:2017CrRes..77...79S. doi:10.1016/j.cretres.2017.05.004. ISSN   0195-6671.
  19. 1 2 Averianov, A. O.; Fayngerts, A. V. (2001). "Early Cretaceous lizards of West Siberia". Voprosy gerpetologii: materialy Pervogo syezda Gerpetolog. ob-va im. A.M. Nikolskogo (in Russian). Pushchino; M.: 6–7.
  20. ↑ 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.
  21. ↑ Fiorelli, L.E.; Calvo, J.O. (2007). "The first "protosuchian" (Archosauria: Crocodyliformes) from the Cretaceous (Santonian) of Gondwana" (PDF).
  22. ↑ Averianov, Alexander O.; Ivantsov, Stepan V.; Leshchinskiy, Sergey V.; Skutschas, Pavel P. (2022-09-01). "First pterosaur bone from the Lower Cretaceous of Siberia, Russia". Cretaceous Research. 137: 105230. Bibcode:2022CrRes.13705230A. doi:10.1016/j.cretres.2022.105230. ISSN   0195-6671. S2CID   248136173.
  23. ↑ Skutschas, P. (2006). "Mesozoic amphibians from Siberia, Russia". 9th International Symposium on Mesozoic Terrestrial Ecosystems and Biota, Abstracts and Proceedings Volume: 123–126.
  24. ↑ 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.
  25. ↑ 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.
  26. 1 2 3 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.
  27. ↑ Averianov, Alexander O.; Lopatin, Alexey V. (2023-07-10). "A long-necked theropod from the Lower Cretaceous of Western Siberia, Russia". Journal of Vertebrate Paleontology. doi:10.1080/02724634.2023.2216761. ISSN   0272-4634.
  28. ↑ 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. Bibcode:2020CrRes.10704309A. doi:10.1016/j.cretres.2019.104309. S2CID   210619334.
  29. ↑ Averianov, A.; Podlesnov, A.; Slobodin, D.; Skutschas, P.; Feofanova, O.; Vladimirova, O. (2023). "First sauropod dinosaur remains from the Early Cretaceous Shestakovo 3 locality, Western Siberia, Russia". Biological Communications. 68 (4): 236–252. doi:10.21638/spbu03.2023.404.
  30. 1 2 Averianov, A. O.; Leshchinskiy, S. V.; Skutschas, P. P.; Fayngertz, A. V.; Rezvyi, A. S. (2004). "Dinosaurs from the Early Cretaceous Ilek Formation in West Siberia, Russia". Second European Association of Vertebrate Paleontologists Meeting. Abstracts of Papers. 6: 6.
  31. ↑ 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.
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