Guanling Formation

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Guanling Formation
Stratigraphic range: early-mid Anisian (Pelsonian)
~247–245  Ma
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Type Geological formation
Underlies Yangliujing Formation
Overlies Jialingjiang Formation
Lithology
Primary Mudstone, limestone
Other Dolomite
Location
Coordinates 25°30′N104°54′E / 25.5°N 104.9°E / 25.5; 104.9
Approximate paleocoordinates 11°42′N94°12′E / 11.7°N 94.2°E / 11.7; 94.2
Region Guizhou & Yunnan Provinces
CountryFlag of the People's Republic of China.svg  China
Extent Yunnan–Guizhou Plateau
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Guanling Formation (China)
China Guizhou location map.jpg
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Guanling Formation (Guizhou)

The Guanling Formation is a Middle Triassic (Anisian or Pelsonian in the regional chronostratigraphy) geologic formation in southwestern China.

Contents

Geology

The formation encompasses two members. The first member is primarily calcareous mudstone and dolomite, indicative of a coastal environment. The second member is a thicker marine sequence of dark micritic limestone with some dolomite. Two distinct fossil assemblages are found in the second member. The older Luoping biota preserves abundant arthropods (including isopods, [1] decapods, [2] mysidaceans and thylacocephalans [3] ) along with fossils from other invertebrates and vertebrates, which are rare but well-preserved. The slightly younger Panxian fauna has a more diverse and common assortment of marine reptiles such as sauropterygians. [4]

A tuff bed in the Luoping biota has been dated to 244.5 ± 2.2 Ma via U-Pb SHRIMP dating. The Luoping biota as a whole was deposited over a period of 340 ± 71 kyr. This estimate is justified by cyclostratigraphic evidence, as indicated by fluctuations of terrestrial proxy metals. [5]

Fossil content

Among others, the following fossils were reported from the formation:

Ichthyopterygia

Ichthyosauria
GenusSpeciesMemberNotesImage
Barracudasauroides [6] B. panxianensisUpper Member [6] [4] A small mixosaurid ichthyosaur, either a member of its own genus [7] or a species of Mixosaurus . [4]
Phalarodon [8] [9] P. cf. fraasi [8] Upper Member [4] Known from a skull of a small mixosaurid ichthyosaur with durophagous dentition.
P. atavus [9] Upper Member [4] A small mixosaurid ichthyosaur known from a complete skeleton. Might represent a member of its own genus, Contectopalatus .
Xinminosaurus [10] X. catactesUpper Member [4] A medium-sized early ichthyosaur with durophagous dentition, possibly a member of Cymbospondylidae.

Sauropterygia

Placodontiformes
GenusSpeciesMemberNotesImage
Atopodentatus [11] A. unicusUpper Member [11] A bizarre, likely herbivorous [12] sauropterygian with possible placodontiform affinities, [13] known from several well-preserved specimens.
Placodus [14] P. inexpectatusUpper Member [14] [4] A medium-sized placodontid placodont, known from a complete specimen. [14]
Saurosphargidae
GenusSpeciesMemberNotesImage
Largocephalosaurus L. polycarpon [15] Upper Member [15] [4] A mid-sized basal saurosphargid sauropterygian.
L. qianensis [16] Upper Member [16] [4] A mid-sized basal saurosphargid sauropterygian.
Sinosaurosphargis [17] S. yunguinensisUpper Member [17] [4] A small armoured saurosphargid sauropterygian.

References

  1. Fu, Wan-Lu; Wilson, George D. F.; Jiang, Da-Yong; Sun, Yuan-Lin; Hao, Wei-Cheng; Sun, Zuo-Yu (September 2010). "A New Species of Protamphisopus Nicholls (Crustacea, Isopoda, Phreatoicidea) from Middle Triassic Luoping Fauna of Yunnan Province, China". Journal of Paleontology. 84 (5): 1003–1013. doi:10.1666/10-042.1. ISSN   0022-3360.
  2. Feldmann, Rodney M.; Schweitzer, Carrie E.; Hu, Shixue; Zhang, Qiyue; Zhou, Changyoing; Xie, Tao; Huang, Jinyuan; Wen, Wen (May 2012). "Macrurous Decapoda from the Luoping Biota (Middle Triassic) of China". Journal of Paleontology. 86 (3): 425–441. doi:10.1666/11-113.1. ISSN   0022-3360.
  3. Feldmann, Rodney M.; Schweitzer, Carrie E.; Hu, Shixue; Huang, Jinyuan; Zhou, Changyong; Zhang, Qiyue; Wen, Wen; Xie, Tao; Maguire, Evin (November 2015). "Spatial distribution of Crustacea and associated organisms in the Luoping Biota (Anisian, Middle Triassic), Yunnan Province, China: evidence of periodic mass kills". Journal of Paleontology. 89 (6): 1022–1037. doi:10.1017/jpa.2015.60. ISSN   0022-3360.
  4. 1 2 3 4 5 6 7 8 9 10 Benton, Michael J.; Zhang, Qiyue; Hu, Shixue; Chen, Zhong-Qiang; Wen, Wen; Liu, Jun; Huang, Jinyuan; Zhou, Changyong; Xie, Tao; Tong, Jinnan; Choo, Brian (2013-10-01). "Exceptional vertebrate biotas from the Triassic of China, and the expansion of marine ecosystems after the Permo-Triassic mass extinction". Earth-Science Reviews. 125: 199–243. Bibcode:2013ESRv..125..199B. doi:10.1016/j.earscirev.2013.05.014. ISSN   0012-8252.
  5. Ma, Zhixin; Wu, Huaichun; Hu, Shixue; Fang, Qiang; Liu, Xiting; Zhou, Changyong; Wen, Wen; Zhang, Qiyue; Huang, Jinyuan; Min, Xiao (2023-09-26). "Temporal duration and preservation mechanism of the Middle Triassic Luoping biota from South China constrained by geochronology and cyclostratigraphy". Global and Planetary Change. 229: 104254. Bibcode:2023GPC...22904254M. doi:10.1016/j.gloplacha.2023.104254. ISSN   0921-8181. S2CID   263214751.
  6. 1 2 Jiang, Da-Yong; Schmitz, Lars; Hao, Wei-Cheng; Sun, Yuan-Lin (March 30, 2006). "A new mixosaurid ichthyosaur from the Middle Triassic of China". Journal of Vertebrate Paleontology. 26 (1): 60–69. doi:10.1671/0272-4634(2006)26[60:ANMIFT]2.0.CO;2. JSTOR   4524536. S2CID   55171917.
  7. Maisch, Michael W. (2010). "Phylogeny, systematics, and origin of the Ichthyosauria - the state of the art". Palaeodiversity. 3: 141–214.
  8. 1 2 Jiang, Da-Yong; Lars, Schmitz; Motani, Ryosuke; Hao, Wie-Cheng; Sun, Yuan-Lin (2007). "The Mixosaurid Ichthyosaur Phalarodon cf. P. fraasi from the Middle Triassic of Guizhou Province, China". Journal of Paleontology. 81 (3): 602–605. Bibcode:2007JPal...81..602J. doi:10.1666/05092.1. JSTOR   4498810. S2CID   54761545.
  9. 1 2 Liu, Jun; Motani, Ryosuke; Jiang, Da-Yong; Hu, Shi-Xue; Aitchison, Jonathan C.; Rieppel, Olivier; Benton, Michael J.; Zhang, Qi-Yue; Zhou, Chang-Yong (2013). "The first specimen of the Middle Triassic Phalarodon atavus (Ichthyosauria: Mixosauridae) from South China, showing postcranial anatomy and peri-Tethyan distribution". Palaeontology. 56 (4): 849–866. Bibcode:2013Palgy..56..849L. doi:10.1111/pala.12021.
  10. Jiang, Da-Yong; Motani, Ryosuke; Hao, Wei-Cheng; Schmitz, Lars; Rieppel, Olivier; Sun, Yuan-Lin; Sun, Zuo-Yu (2008). "New primitive ichthyosaurian (Reptilia, Diapsida) from the Middle Triassic of Panxian, Guizhou, southwestern China and its position in the Triassic biotic recovery". Progress in Natural Science. 18 (10): 1315–1319. Bibcode:2008PNSMI..18.1315J. doi: 10.1016/j.pnsc.2008.01.039 .
  11. 1 2 Cheng, Long; Chen, Xiao-Hong; Shang, Qing-Hua; Wu, Xiao-Chun (2014). "A new marine reptile from the Triassic of China, with a highly specialized feeding adaptation". Naturwissenschaften. 101 (3): 251–259. Bibcode:2014NW....101..251C. doi:10.1007/s00114-014-1148-4. PMID   24452285. S2CID   7770583.
  12. Chun, Li; Rieppel, Olivier; Long, Cheng; Fraser, Nicholas C. (2016). "The earliest herbivorous marine reptile and its remarkable jaw apparatus". Science Advances. 2 (5): e1501659. Bibcode:2016SciA....2E1659C. doi:10.1126/sciadv.1501659. PMC   4928886 . PMID   27386529.
  13. Wolniewicz, Andrzej S.; Shen, Yuefeng; Li, Qiang; Sun, Yuanyuan; Qiao, Yu; Chen, Yajie; Hu, Yi-Wei; Liu, Jun (2023). "An armoured marine reptile from the Early Triassic of South China and its phylogenetic and evolutionary implications". eLife. 12: e83163. doi: 10.7554/eLife.83163 . PMC   10499374 . PMID   37551884.
  14. 1 2 3 Jiang, Da-Yong; Motani, Ryosuke; Hao, Wei-Cheng; Rieppel, Olivier; Sun, Yuan-Lin; Schmitz, Lars; Sun, Zu-Yu (2008). "First Record of Placodontoidea (Reptilia, Sauropterygia, Placodontia) from the Eastern Tethys". Journal of Vertebrate Paleontology. 28 (3): 904–908. doi:10.1671/0272-4634(2008)28[904:FROPRS]2.0.CO;2. JSTOR   20491013. S2CID   9784064.
  15. 1 2 Cheng, Long; Chen, Xiahong; Zeng, Xiongwei; Cai, Yongjian (2012). "A new eosauropterygian (Diapsida: Sauropterygia) from the Middle Triassic of Luoping, Yunnan Province". Journal of Earth Science. 23 (1): 33–40. Bibcode:2012JEaSc..23...33C. doi:10.1007/s12583-012-0231-z.
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  17. 1 2 Li, Chun; Rieppel, Olivier; Wu, Xiao-Chun; Zhao, Li-Jun; Wang, Li-Ting (2011). "A new Triassic marine reptile from southwestern China". Journal of Vertebrate Paleontology. 31 (2): 303–312. Bibcode:2011JVPal..31..303L. doi:10.1080/02724634.2011.550368.
  18. Wang, W.; Lei, H.; Li, C. (2023). "A small-sized dinocephalosaurid archosauromorph from the Middle Triassic of Yunnan, southwestern China". Vertebrata PalAsiatica. 62 (1): 13. doi:10.19615/j.cnki.2096-9899.231013.
  19. Xu, G.-H.; Ma, X.-Y. (2023). "A new basal ginglymodian fish (Holostei: Neopterygii) from the Middle Triassic (Anisian) Luoping Biota, Yunnan, China". Zoological Journal of the Linnean Society. doi:10.1093/zoolinnean/zlad144.
  20. 1 2 3 Lu, Yu-Ting; Liu, Jun (2023-10-02). "A new tanystropheid (Diapsida: Archosauromorpha) from the Middle Triassic of SW China and the biogeographical origin of Tanystropheidae". Journal of Systematic Palaeontology. 21 (1). Bibcode:2023JSPal..2150778L. doi:10.1080/14772019.2023.2250778. ISSN   1477-2019. S2CID   263634664.
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