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Guanling Formation

Summary

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

Guanling Formation
Stratigraphic range: early-mid Anisian (Pelsonian)
~247–245 Ma
↓
TypeGeological formation
UnderliesYangliujing Formation
OverliesJialingjiang Formation
Lithology
PrimaryMudstone, limestone
OtherDolomite
Location
Coordinates25°30′N 104°54′E / 25.5°N 104.9°E / 25.5; 104.9
Approximate paleocoordinates11°42′N 94°12′E / 11.7°N 94.2°E / 11.7; 94.2
RegionGuizhou & Yunnan Provinces
Country China
ExtentYunnan–Guizhou Plateau
Guanling Formation is located in China
Guanling Formation
Guanling Formation (China)
Guanling Formation is located in Guizhou
Guanling Formation
Guanling Formation (Guizhou)

Geology edit

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 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.[1]

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.[2]

Fossil content edit

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

Ichthyopterygia edit

Ichthyosauria
Genus Species Member Notes Image
Barracudasauroides[3] B. panxianensis Upper Member[3][1] A small mixosaurid ichthyosaur, either a member of its own genus[4] or a species of Mixosaurus.[1]
Phalarodon[5][6] P. cf. fraasi[5] Upper Member[1] Known from a skull of a small mixosaurid ichthyosaur with durophagous dentition.
P. atavus[6] Upper Member[1] A small mixosaurid ichthyosaur known from a complete skeleton. Might represent a member of its own genus, Contectopalatus.
Xinminosaurus[7] X. catactes Upper Member[1] A medium-sized early ichthyosaur with durophagous dentition, possibly a member of Cymbospondylidae.

Sauropterygia edit

Placodontiformes
Genus Species Member Notes Image
Atopodentatus[8] A. unicus Upper Member[8] A bizarre, likely herbivorous[9] sauropterygian with possible placodontiform affinities,[10] known from several well-preserved specimens.
Placodus[11] P. inexpectatus Upper Member[11][1] A medium-sized placodontid placodont, known from a complete specimen.[11]
Saurosphargidae
Genus Species Member Notes Image
Largocephalosaurus L. polycarpon[12] Upper Member [12][1] A mid-sized basal saurosphargid sauropterygian.
L. qianensis[13] Upper Member [13][1] A mid-sized basal saurosphargid sauropterygian.
Sinosaurosphargis[14] S. yunguinensis Upper Member [14][1] A small armoured saurosphargid sauropterygian.

References edit

  1. ^ a b c d e f g h i j 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.
  2. ^ 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.
  3. ^ a b 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.
  4. ^ Maisch, Michael W. (2010). "Phylogeny, systematics, and origin of the Ichthyosauria - the state of the art". Palaeodiversity. 3: 141–214.
  5. ^ a b 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.
  6. ^ a b 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.
  7. ^ 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. doi:10.1016/j.pnsc.2008.01.039.
  8. ^ a b 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. S2CID 7770583.
  9. ^ 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.
  10. ^ 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. doi:10.7554/eLife.83163. PMC 10499374.
  11. ^ a b c 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.
  12. ^ a b 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: 33–40.
  13. ^ a b Li, Chun; Jiang, Da-Yong; Cheng, Long; Wu, Xiao-Chun; Rieppel, Olivier (2014). "A new species of Largocephalosaurus (Diapsida: Saurosphargidae), with implications for the morphological diversity and phylogeny of the group". Geological Magazine. 151 (1): 100–120. doi:10.1017/S001675681300023X.
  14. ^ a b 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. doi:10.1080/02724634.2011.550368.
  15. ^ 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.
  16. ^ a b c 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.
  17. ^ Xu, G.-H.; Shang, Q.-H.; Wang, W.; Ren, Y.; Lei, H.; Liao, J.-L.; Zhao, L.-J.; Li, C. (2023). "A new long-snouted marine reptile from the Middle Triassic of China illuminates pachypleurosauroid evolution". Scientific Reports. 13 (1). 16. Bibcode:2023NatSR..13...16X. doi:10.1038/s41598-022-24930-y. ISSN 2045-2322. PMC 9816097. PMID 36604433.

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