The Yanan Formation, alternatively spelled the Yan'an Formation (Chinese: 延安组), is a geological formation in China, it is also alternatively considered a group. The age of the formation is uncertain, with estimates ranging from Toarcian to Bajocian. It is divided up into 5 members, with the designation of Y1 through Y5. Y2, Y3 and Y4 are predominantly dark shales, while Y1 and Y5 are composed of sandstones, coal beds[1] and interbedded mudstones. The depositional environment at the time was when the Ordos Basin formed a large inland lake, surrounded by floodplains. The dark shales have been explored for the potential of producing shale gas.[2] The coal has also been explored for the production of coalbed methane.[3] The formation is also notable for its fossil content, with dinosaur footprints having been found in the formation.[4] The dinosaur Lingwulong was formerly thought to have been found in this formation,[5] but the strata was later attributed to the overlying Zhiluo Formation.[6]
Fossil content
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Color key
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Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.
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Dinosaurs
Sauropods
Insects
References
- ^ Ao, Weihua; Huang, Wenhui; Weng, Chengmin; Xiao, Xiuling; Liu, Dameng; Tang, Xiuyi; Chen, Ping; Zhao, Zhigen; Wan, Huan (January 2012). "Coal petrology and genesis of Jurassic coal in the Ordos Basin, China". Geoscience Frontiers. 3 (1): 85–95. Bibcode:2012GeoFr...3...85A. doi:10.1016/j.gsf.2011.09.004. ISSN 1674-9871.
- ^ Wang, Dong-dong; Shao, Long-yi; LI, Zhi-xue; LI, Ming-pei; Lv, Dawei; Liu, Haiyan (September 2016). "Hydrocarbon generation characteristics, reserving performance and preservation conditions of continental coal measure shale gas: A case study of Mid-Jurassic shale gas in the Yan'an Formation, Ordos Basin". Journal of Petroleum Science and Engineering. 145: 609–628. Bibcode:2016JPSE..145..609W. doi:10.1016/j.petrol.2016.06.031. ISSN 0920-4105.
- ^ Xu, H.; Tang, D.Z.; Liu, D.M.; Tang, S.H.; Yang, F.; Chen, X.Z.; He, W.; Deng, C.M. (June 2012). "Study on coalbed methane accumulation characteristics and favorable areas in the Binchang area, southwestern Ordos Basin, China". International Journal of Coal Geology. 95: 1–11. Bibcode:2012IJCG...95....1X. doi:10.1016/j.coal.2012.02.001. ISSN 0166-5162.
- ^ Xing, Lida; Lockley, Martin G.; Tang, Yonggang; Klein, Hendrik; Zhang, Jianping; Persons, W. Scott; Dai, Hui; Ye, Yong (2015-01-02). "Theropod and Ornithischian Footprints from the Middle Jurassic Yanan Formation of Zizhou County, Shaanxi, China". Ichnos. 22 (1): 1–11. Bibcode:2015Ichno..22....1X. doi:10.1080/10420940.2014.985670. ISSN 1042-0940. S2CID 129509962.
- ^ Xu, Xing; Upchurch, Paul; Mannion, Philip D.; Barrett, Paul M.; Regalado-Fernandez, Omar R.; Mo, Jinyou; Ma, Jinfu; Liu, Hongan (2018-07-24). "A new Middle Jurassic diplodocoid suggests an earlier dispersal and diversification of sauropod dinosaurs". Nature Communications. 9 (1): 2700. Bibcode:2018NatCo...9.2700X. doi:10.1038/s41467-018-05128-1. ISSN 2041-1723. PMC 6057878. PMID 30042444.
- ^ a b Dai, Hui; Tan, Chao; Xiong, Can; Ma, Qingyu; Li, Ning; Yu, Haidong; Wei, Zhaoying; Wang, Ping; Yi, Jian; Wei, Guangbiao; You, Hailu; Ren, Xinxin (2022). "New macronarian from the Middle Jurassic of Chongqing, China: phylogenetic and biogeographic implications for neosauropod dinosaur evolution". Royal Society Open Science. 9 (11): 220794. Bibcode:2022RSOS....920794D. doi:10.1098/rsos.220794. PMC 9627447. PMID 36340515.
However, valid Middle Jurassic neosauropods are rarely reported before the discovery of dicraeosaurid Lingwulong from middle/late Middle Jurassic (late Bathonian–early Callovian) (The horizon was revised from Yan'an Formation (Aalenian–Bajocian) to Zhiluo Formation (Bathonian–early Oxfordian)
- ^ Xing Xu; Paul Upchurch; Philip D. Mannion; Paul M. Barrett; Omar R. Regalado-Fernandez; Jinyou Mo; Jinfu Ma; Hongan Liu (2018). "A new Middle Jurassic diplodocoid suggests an earlier dispersal and diversification of sauropod dinosaurs". Nature Communications. 9 (1) 2700. Bibcode:2018NatCo...9.2700X. doi:10.1038/s41467-018-05128-1. PMC 6057878. PMID 30042444.
- ^ Zheng, D.; Dong, C.; Wang, H.; Ye, Y.; Wang, B.; Chang, S.-C.; Zhang, H. (2017). "The first damsel-dragonfly (Odonata: Isophlebioidea: Campterophlebiidae) from the Middle Jurassic of Shaanxi Province, northwestern China". Alcheringa: An Australasian Journal of Palaeontology. 41 (4): 509–513. doi:10.1080/03115518.2017.1318170. S2CID 133806124.
- ^ Fu, Y.; Xu, M.; Gao, J.; Huang, D. (2023). "The Archijassidae from the Jurassic of China (Hemiptera, Cicadomorpha, Membracoidea) and its palaeoecological significance". Historical Biology: An International Journal of Paleobiology. 36 (10): 2233–2238. doi:10.1080/08912963.2023.2250109. S2CID 261636256.
- ^ Lian, X.-N.; Cai, C.-Y.; Feng, Z.; Huang, D.-Y. (2024). "New orthophlebiid mecopteran from the Middle Jurassic Yan'an Formation, China". Journal of Insect Biodiversity. 60 (1): 47–54. doi:10.12976/jib/2024.60.1.8.
- ^ Tian, F.; Zheng, D.; Nel, A.; Ye, Y.; Mei, T.; Zhang, H. (2023). "A new campterophlebiid damsel-dragonfly (Odonata: Isophlebioidea) from the Middle Jurassic Yanan Formation of Yulin City, Shaanxi Province, NW China". Comptes Rendus Palevol. 22 (23): 491–496. doi:10.5852/cr-palevol2023v22a23. S2CID 259852598.
- ^ Huang, D.Y. (2023). "Discovery of Thripida from the Middle Jurassic Yan'an Formation". Zootaxa. 5396 (1): 22–25. doi:10.11646/zootaxa.5396.1.6. PMID 38220986. S2CID 266659877.
- ^ Fu, Y.; Huang, D. (2020). "A new fossil cercopoid from the middle Jurassic Ordos and Jiyuan basins, northern China (Hemiptera, Cicadomorpha)". Historical Biology: An International Journal of Paleobiology. 33 (10): 2025–2030. doi:10.1080/08912963.2020.1765167. S2CID 219747247.
- ^ Liang, Junhui; Shih, Chungkun; Ren, Dong (2019), Ren, Dong; Shih, Chung Kun; Gao, Taiping; Yao, Yunzhi; Wang, Yongjie (eds.), "Blattaria – Cockroaches", Rhythms of Insect Evolution: Evidence from the Jurassic and Cretaceous in Northern China, pp. 91–112, doi:10.1002/9781119427957.ch7, ISBN 978-1-119-42795-7
- ^ a b Nel, A.; Xu, M.; Wang, Y.; Song, X.; Gao, J.; Ji, G.; Huang, D. (2024). "New Chinese Jurassic damsel-dragonflies of the families Paragonophlebiidae, Selenothemistidae and Isophlebiidae (Odonata, Epiproctophora) from the Jurassic Ordos Basin of NW China". Geobios. 87: 37–44. doi:10.1016/j.geobios.2024.08.014.
- ^ Nel, A.; Huang, D.-Y. (2024). "New locustopsid fossils from the Middle Jurassic Yan'an Formation (Orthoptera: Caelifera)". Journal of Insect Biodiversity. 60 (1): 16–23.
- ^ a b Xu, M.-M.; Hakim, M.; Huang, D.-Y. (2023). "New Jurassic protopsyllidiids from the Yan'an Formation, North China (Insecta: Hemiptera)". Palaeoentomology. 6 (5): 542–548. doi:10.11646/palaeoentomology.6.5.13. S2CID 264597972.
- ^ Guo, Q.-M.; Xu, C.-P.; Nel, A.; Peng, A.-C.; Wen, Z.-G.; Li, T.; Fang, R.; Zheng, D.-R. (2025). "A new genus and species of Susumaniidae (Insecta: Phasmatodea) from the Middle Jurassic of Shaanxi Province, Northwest China". Palaeoworld. 34 (5) 200942. doi:10.1016/j.palwor.2025.200942.
- ^ Jouault, C. (2024). "A new parapamphiliin wasp (Hymenoptera: Sepulcidae) from the Middle Jurassic Yan'an Formation, China". Journal of Insect Biodiversity. 60 (1): 83–88. doi:10.12976/jib/2024.60.1.12.