Miaogou Formation

Miaogou Formation
Stratigraphic range: late Early Cretaceous, ~Aptian–Albian PreꞒ Ꞓ O S D C P T J K Pg N
Type	Geological formation
Unit of	Yangtaiwatan Basin [1]
Underlies	Baiyanghe Formation [2]
Lithology
Primary	Sandstone, mudstone, muddy limestone and sandy conglomerate [1]
Location
Coordinates	40°12′N105°44′E / 40.200°N 105.733°E / 40.200; 105.733
Region	Inner Mongolia
Country	China
Miaogou Formation (China) Show map of China Miaogou Formation (Inner Mongolia) Show map of Inner Mongolia

The Miaogou Formation is a geological formation in Inner Mongolia, north China. While its absolute age is uncertain, it has been estimated to represent Early Cretaceous sediments based on the faunal composition. Dinosaur remains are among the fossils that have been recovered from the formation.

History and geology

The primary fossil-producing outcrop of the Miaogou Formation is the Maortu locality, which was discovered in 1959 by a joint expedition of Chinese and Russian paleontologists. ^[3] Initial reports of the locality's fauna incorrectly assigned the fossils to either the Ulansuhai or Dashuigou formations, but a later discussion corrected this. ^[4]

While the Miaogou Formation has not been absolutely dated, estimates based on charophytan, stratigraphic, and sedimentological studies have proposed a Barremian–Albian age range. ^[5] However, a more narrow range (around Aptian-Albian) is implied based on the fossil animals found in the formation, which are inconsistent with Chinese Barremian faunas such as those associated with the Jehol Biota. ^[4]

Paleoenvironment

Analysis of the formation's geology indicates that it represents a hot, humid environment with large lake systems. ^[3] The formation's lower member preserves alluvial fan to braided stream deposits, while the upper member preserves meandering stream and lacustrine deposits. ^[6]

Fossil content

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Dinosaurs

Genus	Species	Region	Material	Notes	Images
Gobisaurus	G. domoculus	Maortu locality, Chilantai	A skull, with undescribed postcranial remains belonging to the same individual [7]	An ankylosaurid closely related to Shamosaurus ; originally interpreted as from the nearby Ulansuhai Formation [4]
Probactrosaurus	P. gobiensis	Maortu locality, Chilantai	Partial skulls and skeletons [8]	A hadrosauroid ornithopod; originally interpreted as from the nearby Dashuigou Formation [4]
Shaochilong	S. maortuensis	Maortu locality, Chilantai	Partial skull, axis, and caudal vertebrae [9]	A tetanuran theropod, formerly " Chilantaisaurus " maortuensis; originally interpreted as from the nearby Ulansuhai Formation [4]
Yuanyanglong	Y. bainian	Maortu locality, Chilantai	Two associated partial skeletons of similarly sized individuals [4]	A basal oviraptorosaurian theropod

See also

• List of stratigraphic units with few dinosaur genera

References

1. Zhang, Shuai; Liu, Lihui; Liu, Qinfu; Zhang, Bingjie; Qiao, Zhichuan; Teppen, Brian J. (February 2021). "Genesis of Palygorskite in the Neogene Baiyanghe Formation in Yangtaiwatan Basin, Northwest China, Based on the Mineralogical Characteristics and Occurrence of Enriched Trace Elements and Ree". Clays and Clay Minerals. 69 (1): 23–37. doi:10.1007/s42860-020-00104-7. ISSN   0009-8604.
2. Liu, Lihui; Zhang, Shuai; Liu, Qinfu; Liu, Linsong; Deng, Youjun (September 2021). "Palaeoclimate, palaeosalinity and redox conditions control palygorskite claystone formation: an example from the Yangtaiwatan Basin, northwest China". Clay Minerals. 56 (3): 210–221. doi:10.1180/clm.2022.1. ISSN   0009-8558.
3. Kliebanova, I. M. (1963). "阿拉善地区(毛尔图)白堊纪恐龙的埋藏" [Deposit of Mesozoic Dinosaurs in Alashan (Maortu)](PDF). Vertebrata PalAsiatica (in Chinese). 7 (1): 52–58. doi:10.19615/j.cnki.1000-3118.1963.01.005.
4. Hao, Mingze; Li, Zhiyu; Wang, Zhili; Wang, Shuqiong; Ma, Feimin; Qinggele; King, J. Logan; Pei, Rui; Zhao, Qi; Xu, Xing (2024-10-24). "A new oviraptorosaur from the Lower Cretaceous Miaogou Formation of western Inner Mongolia, China" . Cretaceous Research (in press): 106023. doi:10.1016/j.cretres.2024.106023.
5. Van Itterbeeck, Jimmy; Bultynck, Pierre; Li, Guo Wen; Vandenberghe, Noel (2001). "Stratigraphy, sedimentology and palaeoecology of the dinosaur-bearing Cretaceous strata at Dashuiguo (Inner Mongolia, People's Republic China)" (PDF). Bulletin van het Koninklijk Belgisch Instituut voor Natuurwetenschappen. 71: 51–66.
6. Wang, Zheng Qi; Guan, Tai Yang (2004). "Uranium pre-concentration in Miaogou Formation, Lower Cretaceous and its prospecting significance in Chaoshui Basin". Uranium Geology (in Chinese). 20 (5): 279–285.
7. Vickaryous, Matthew K; Russell, Anthony P; Currie, Philip J; Zhao, Xi-Jin (2001-12-01). "A new ankylosaurid (Dinosauria: Ankylosauria) from the Lower Cretaceous of China, with comments on ankylosaurian relationships". Canadian Journal of Earth Sciences . 38 (12): 1767–1780. doi:10.1139/e01-051. ISSN   0008-4077.
8. Norman, David B. (2002-08-21). "On Asian ornithopods (Dinosauria: Ornithischia). 4. Probactrosaurus Rozhdestvensky, 1966". Zoological Journal of the Linnean Society . 136 (1): 113–144. doi:10.1046/j.1096-3642.2002.00027.x. ISSN   1096-3642.
9. Brusatte, S.; Benson, R.; Chure, D.; Xu, X.; Sullivan, C.; Hone, D. (2009). "The first definitive carcharodontosaurid (Dinosauria: Theropoda) from Asia and the delayed ascent of tyrannosaurids". Naturwissenschaften. 96 (9): 1051–1058. Bibcode:2009NW.....96.1051B. doi:10.1007/s00114-009-0565-2. hdl: 20.500.11820/33528c2e-0c9c-4160-8693-984f077ee5d0 . PMID   19488730. S2CID   25532873.