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Ilek Formation
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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]
Key Information
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
[edit]
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
[edit]Amphibians
[edit]| Genus | Species | Locality | Material | Notes | Images |
|---|---|---|---|---|---|
| Kiyatriton | K. leshchinskiyi[7] |
|
Atlas, trunk vertebrae, fragmentary dentaries, femora, humerus, and nearly complete ilium | A crown-group salamander | |
| Kuzbassia | K. sola[8] |
|
Two atlantal centra and a trunk vertebral centrum | A karaurid |
Mammaliamorphs
[edit]| Genus | Species | Locality | Material | Notes | Images |
|---|---|---|---|---|---|
| Acinacodus | A. tagaricus[9] | Right dentary fragment | An amphidontid mammal | ||
| Baidabatyr | B. clivosus[10] |
|
Upper premolar | A multituberculate | |
| Gobiconodon | G. borissiaki[11] | 21 upper and lower jaws. | A gobiconodont | ||
| G. hoburensis[12] | A fragmentary lower jaw. | ||||
| Kemchugia | K. magna[13] | A tooth | An amphilestid mammal | ||
| Kiyatherium | K. cardiodens[14] | A maxilla | A zhangheotheriid mammal | ||
| Sibirotherium | S. rossicum[15] |
|
M1 tooth;[15] mandibular fragments[16] | A docodontan mammaliaform | |
| Xenocretosuchus | X. sibiricus[17] | Dental elements | A tritylodontid mammaliamorph | ||
| Yermakia | Y. domitor[13] |
|
A mandible | A tinodontid mammal |
Choristoderes
[edit]| Genus | Species | Locality | Material | Notes | Images |
|---|---|---|---|---|---|
| cf. Khurendukhosaurus[18] | K. cf. sp |
|
Dorsal vertebra, sacral vertebra | A non-neochoristodere choristodere | |
| "Shestakovo choristodere"[18] |
|
Fragmentary dentaries, several vertebrae, rib fragments | A possible neochoristodere | ||
| Choristodera[18] | Indeterminate |
|
Cervical centrum | May represent a taxon distinct from both Khurendukhosaurus and the "Shestakovo choristodere" | |
Lizards
[edit]| Genus | Species | Locality | Material | Notes | Images |
|---|---|---|---|---|---|
| Paramacellodidae | Indeterminate[4] |
|
|||
| Platynota | Indeterminate[4] |
|
|||
| Xenosauridae | Indeterminate[4] |
|
A knob-scaled lizard |
Turtles
[edit]| Genus | Species | Locality | Material | Notes | Images |
|---|---|---|---|---|---|
| Kirgizemys | A macrobaenid |
Crocodylomorphs
[edit]| Genus | Species | Locality | Material | Notes | Images |
|---|---|---|---|---|---|
| Kyasuchus | K. saevi[19] |
|
A partial skull | A shartegosuchid crocodyliform | |
| Tagarosuchus | T. kulemzini[20] |
|
Nearly complete skull | A crocodyliform |
Pterosaurs
[edit]| Genus | Species | Locality | Material | Notes | Image |
|---|---|---|---|---|---|
| ?Ctenochasmatidae | Indeterminate[13] |
|
|||
| Lonchognathosaurus | L. cf. sp.[21] |
|
Wing metacarpal fragment | A dsungaripterid | |
| Ornithocheiridae | Indeterminate[22] |
|
|||
| Pterodactyloidea | Indeterminate[13] |
|
Dinosaurs
[edit]Sauropodomorphs
[edit]| Genus | Species | Locality | Material | Notes | Images |
|---|---|---|---|---|---|
| Lithostrotia | Indeterminate[23] | Caudal vertebrae | Potentially three distinct taxa of titanosaur | ||
| Sibirotitan | S. astrosacralis[5] |
|
Vertebrae, sacrum, and pedal elements | A somphospondylan sauropod |  |
Ornithischians
[edit]| Genus | Species | Locality | Material | Notes | Images |
|---|---|---|---|---|---|
| Ornithischia | Indeterminate[4] |
|
Isolated teeth | Originally identified as two distinct "hypsilophodontid" taxa[25] | |
| Psittacosaurus | P. sibiricus[26] |
|
Several skeletons | A ceratopsian |  |
| Stegosauria | Indeterminate[13] |
|
Isolated teeth[25] |
Theropods
[edit]| Genus | Species | Locality | Material | Notes | Images |
|---|---|---|---|---|---|
| Evgenavis | E. nobilis[27] | A set of limb elements | A confuciusornithiform |  | |
| Kiyacursor | K. longipes[28] |
|
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 | .png) |
| Paraves | Indeterminate[29] | Teeth | May belong to either Microraptorinae or Troodontidae | ||
| Mystiornis | M. cyrili[30] |
|
Isolated metatarsus | An avisaurid enantiornithean |  |
| Paraves | Indeterminate[29] | Teeth | May belong to either Microraptorinae or Troodontidae | ||
| Tyrannosauroidea | Indeterminate[29] | Teeth | |||
| Urbacodon | U. cf. sp.[29] | Teeth | A troodontid with unserrated teeth |
See also
[edit]References
[edit]- ^ a b c 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.
- ^ Криштофович А. Н., ed. (1955). "Илекская свита". Геологический словарь. Vol. 1 (А-Л). Рипол Классик. p. 271. ISBN 9785458366533.
{{cite book}}: ISBN / Date incompatibility (help) - ^ Лебедев И. В., ed. (1962). Биостратиграфия мезозойских и третичных отложений Западной Сибири. pp. 168–169.
- ^ a b c d e 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: 627–641. doi:10.1144/SP545-2023-62.
- ^ a b 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.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ Trofimov, B. A. (1978). "The first triconodonts (Mammalia, Triconodonta) from Mongolia". Doklady Akademii Nauk SSSR. 243 (1): 213–216.
- ^ 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.
- ^ a b c d e 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.
- ^ E. N. Maschenko and A. V. Lopatin. 2002. A new Early Cretaceous mammal from Western Siberia. Doklady Biological Sciences 386:475-477
- ^ a b 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.
- ^ 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.
- ^ "Fossilworks: Stereognathus". Archived from the original on 2021-12-13. Retrieved 2021-12-17.
- ^ a b c 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.
- ^ 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.
- ^ Fiorelli, L.E.; Calvo, J.O. (2007). "The first "protosuchian" (Archosauria: Crocodyliformes) from the Cretaceous (Santonian) of Gondwana" (PDF).
- ^ 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.
- ^ Skutschas, P. (2006). "Mesozoic amphibians from Siberia, Russia". 9th International Symposium on Mesozoic Terrestrial Ecosystems and Biota, Abstracts and Proceedings Volume: 123–126.
- ^ 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 104309. Bibcode:2020CrRes.10704309A. doi:10.1016/j.cretres.2019.104309. S2CID 210619334.
- ^ 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.
- ^ a b 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.
- ^ 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.
- ^ 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.
- ^ a b 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. PMC 11285863. PMID 38747705.
- ^ a b c d 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.
- ^ 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.