Guanling Formation

Not to be confused with Guanling biota.

Guanling Formation
Stratigraphic range: early-mid Anisian (Pelsonian) ~247–245  Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
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
Country	China
Extent	Yunnan–Guizhou Plateau
Guanling Formation (China) Show map of China Guanling Formation (Guizhou) Show map of Guizhou

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

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:

Fish

Fish of the Guanling Formation
Genus	Species	Locality	Member	Material	Notes	Image
Altisolepis						Frodoichthys luopingensis Luopingcoelucanthus eurylacrimalis Luoxiongichthys hyperdorsalis
Diandongichthys [6]
Diandongperleidus	D. denticulatus
Feroxichthys
Frodoichthys	F. luopingensis	Dawazi, Yunnan
Gimlichthys
Kyphosichthys	K. grandei	Luoping, eastern Yunnan Province
Luopingcoelacanthus	L. eurylacrimalis				An extinct coelacanth
Luopingperleidus
Luoxiongichthys	L. hyperdorsalis	Luoxiong Town, Yunnan	Lower member	A holotype specimen consists of a nearly complete skeleton and skull, from the paratype LPV-10120, a partial skull, and other referred materials.
Panxianichthys
Platysiagum
Pteronisculus					A prehistoric ray-finned fish
Sangiorgioichthys
Saurichthys					A predatory ray-finned fish
Sinosaurichthys	S. longimedialis	Yangjuan, Guizhou and Dawazi of Luoping, Yunnan	Upper Member		Saurichthyid ray-finned fish
	S. longipectoralis
	S. minuta
Venusichthys
Yelangichthys	Y. macrocephalus
Yudaiichthys
Yunnancoelacanthus	Y. acrotuberculatus				A coelacanthiform

Reptiles

Ichthyopterygia

Ichthyosauria of the Guanling Formation
Genus	Species	Locality	Member	Materials	Notes	Image
Barracudasauroides [7]	B. panxianensis		Upper Member [7] [4]	A skeleton	A small mixosaurid ichthyosaur, either a member of its own genus [8] or a species of Mixosaurus . [4]
Phalarodon [9] [10]	P. cf. fraasi [9]		Upper Member [4]	A skull with durophagous dentition.	A small mixosaurid ichthyosaur
	P. atavus [10]		Upper Member [4]	A complete skeleton	A small mixosaurid ichthyosaur. Might represent a member of its own genus, Contectopalatus .
Xinminosaurus [11]	X. catactes		Upper Member [4]		A medium-sized early ichthyosaur with durophagous dentition, possibly a member of Cymbospondylidae.

Sauropterygia

Placodontiformes

Placodontiformes of the Guanling Formation
Genus	Species	Locality	Member	Materials	Notes	Image
Atopodentatus [12]	A. unicus		Upper Member [12]		A bizarre, likely herbivorous [13] sauropterygian with possible placodontiform affinities, [14] known from several well-preserved specimens.	Atopodentatus Placodus
Placodus [15]	P. inexpectatus		Upper Member [15] [4]		A medium-sized placodontid placodont, known from a complete specimen. [15]

Saurosphargidae

Saurosphargidae of the Guanling Formation
Genus	Species	Locality	Member	Materials	Notes	Image
Largocephalosaurus	L. polycarpon [16]		Upper Member [16] [4]		A mid-sized basal saurosphargid sauropterygian.
	L. qianensis [17]		Upper Member [17] [4]		A mid-sized basal saurosphargid sauropterygian.
Sinosaurosphargis [18]	S. yunguinensis		Upper Member [18] [4]		A small armoured saurosphargid sauropterygian.

• Austronaga ^[19]
• Dawazisaurus
• Diandongosaurus
• Dianopachysaurus
• Dianmeisaurus
• Dinocephalosaurus ^[20]

• Gracilicollum
• Honghesaurus
• Luopingosaurus ^[21]
• Luxisaurus ^[20]
• Mixosaurus
• Nothosaurus
• Pectodens ^[20]
• Qianosuchus
• Sanchiaosaurus
• Trachelosaurus
• Wumengosaurus

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. 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. 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.
7. 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.
8. Maisch, Michael W. (2010). "Phylogeny, systematics, and origin of the Ichthyosauria - the state of the art". Palaeodiversity. 3: 141–214.
9. 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.
10. 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.
11. 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 .
12. 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.
13. 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.
14. 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.
15. 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.
16. 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.
17. 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. Bibcode:2014GeoM..151..100L. doi:10.1017/S001675681300023X.
18. 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.
19. 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.
20. 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.
21. 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.