Ilek Formation

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Ilek Formation
Stratigraphic range: Lower Cretaceous,
Barremian–Aptian
Shestakovsky Yar.jpg
Shestakovo 1 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

Shestakovo 3 locality Shestakovo-3.jpg
Shestakovo 3 locality

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
GenusSpeciesLocalityMaterialNotesImages
Kiyatriton K. leshchinskiyi [7]
  • Shestakovo 1
 Atlas, trunk vertebrae, fragmentary dentaries, femora, humerus, and nearly complete iliumA crown-group salamander
Kuzbassia K. sola [8]
  • Shestakovo 1
Two atlantal centra and a trunk vertebral centrumA karaurid

Mammaliamorphs

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

Choristoderes

Choristoderes reported from the Ilek Formation
GenusSpeciesLocalityMaterialNotesImages
cf. Khurendukhosaurus [18] K. cf. sp
  • 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 [18] Indeterminate
  • Smolenskii Yar
Cervical centrumMay represent a taxon distinct from both Khurendukhosaurus and the "Shestakovo choristodere"

Lizards

Lizards reported from the Ilek Formation
GenusSpeciesLocalityMaterialNotesImages
Paramacellodidae Indeterminate [4]
  • Kemchug assemblage
  • Kiya assemblage
Platynota Indeterminate [4]
  • Kemchug assemblage
Xenosauridae Indeterminate [4]
  • Kemchug assemblage
  • Kiya assemblage
A knob-scaled lizard

Turtles

Turtles reported from the Ilek Formation
GenusSpeciesLocalityMaterialNotesImages
Kirgizemys A macrobaenid

Crocodylomorphs

Crocodylomorphs reported from the Ilek Formation
GenusSpeciesLocalityMaterialNotesImages
Kyasuchus K. saevi [19]
  • Shestakovo 3
A partial skullA shartegosuchid crocodyliform
Tagarosuchus T. kulemzini [20]
  • Shestakovo 3
Nearly complete skullA crocodyliform

Pterosaurs

Pterosaurs reported from the Ilek Formation
GenusSpeciesLocalityMaterialNotesImage
?Ctenochasmatidae Indeterminate [13]
  • Bol'shoi Kemchug 3
Lonchognathosaurus L. cf. sp. [21]
  • Novochernorechensk
Wing metacarpal fragmentA dsungaripterid
Ornithocheiridae Indeterminate [22]
  • Shestakovo 1
Pterodactyloidea Indeterminate [13]
  • Bol'shoi Kemchug 3

Dinosaurs

Sauropodomorphs

Sauropodomorphs reported from the Ilek Formation
GenusSpeciesLocalityMaterialNotesImages
Lithostrotia Indeterminate [23] Caudal vertebraePotentially three distinct taxa of titanosaur
Sibirotitan S. astrosacralis [5]
  • Shestakovo 1
  • Shestakovo 3 [24]
Vertebrae, sacrum, and pedal elementsA somphospondylan sauropod
Sibirotitan model.jpg

Ornithischians

Ornithischians reported from the Ilek Formation
GenusSpeciesLocalityMaterialNotesImages
Ornithischia Indeterminate [4]
  • Shestakovo 1
  • Bol'shoi Kemchug 3
Isolated teethOriginally identified as two distinct "hypsilophodontid" taxa [25]
Psittacosaurus P. sibiricus [26]
  • Shestakovo
Several skeletonsA ceratopsian
Psittacosaurus sibiricus.png
Stegosauria Indeterminate [13]
  • Bol'shoi Kemchug 3
Isolated teeth [25]

Theropods

Theropods reported from the Ilek Formation
GenusSpeciesLocalityMaterialNotesImages
Evgenavis E. nobilis [27] A set of limb elementsA confuciusornithiform
Evgenavis tarsometatarsus.png
Kiyacursor K. longipes [28]
  • Shestakovo 1
Partial skeleton including cervical and caudal vertebrae, cervical and dorsal ribs, a left scapulocoracoid, humeri, and much of both hind limbs [28] A noasaurid theropod
Kiyacursor PM (white bg).png
Paraves Indeterminate [29] TeethMay belong to either Microraptorinae or Troodontidae
Mystiornis M. cyrili [30]
  • Shestakovo 1
Isolated metatarsusAn avisaurid enantiornithean
Mystiornis.png
Paraves Indeterminate [29] TeethMay belong to either Microraptorinae or Troodontidae
Tyrannosauroidea Indeterminate [29] Teeth
Urbacodon U. cf. sp. [29] TeethA troodontid with unserrated teeth

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). Рипол Классик. 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. Bibcode:2014CrRes..51...88S. 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 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. 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. 512 (1): 871–873. Bibcode:2023DokES.512..871L. doi:10.1134/S1028334X23601128. ISSN   1028-334X.
  16. ↑ 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 .
  17. ↑ "Fossilworks: Stereognathus". Archived from the original on 2021-12-13. Retrieved 2021-12-17.
  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. ↑ 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.
  20. ↑ Fiorelli, L.E.; Calvo, J.O. (2007). "The first "protosuchian" (Archosauria: Crocodyliformes) from the Cretaceous (Santonian) of Gondwana" (PDF).
  21. ↑ 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.
  22. ↑ Skutschas, P. (2006). "Mesozoic amphibians from Siberia, Russia". 9th International Symposium on Mesozoic Terrestrial Ecosystems and Biota, Abstracts and Proceedings Volume: 123–126.
  23. ↑ 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.
  24. ↑ 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.
  25. 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.
  26. ↑ 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.
  27. ↑ 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.
  28. 1 2 Averianov, A. O.; Skutschas, P. P.; Atuchin, A. A.; Slobodin, D. A.; Feofanova, O. A.; Vladimirova, O. N. (2024). "The last ceratosaur of Asia: a new noasaurid from the Early Cretaceous Great Siberian Refugium". Proceedings of the Royal Society B: Biological Sciences. 291 (2023). 20240537. doi:10.1098/rspb.2024.0537.
  29. 1 2 3 4 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.
  30. ↑ 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.
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