Guanling Formation
{{Short description|Geological formation in China}}
{{Distinguish|Guanling biota}}
{{Infobox rockunit
| name = Guanling Formation
| image =
| caption =
| type = Geological formation
| age = early-mid Anisian (Pelsonian)
~{{fossil range|247|245}}
| period = Anisian
| prilithology = Mudstone, limestone
| otherlithology = Dolomite
| namedfor =
| namedby =
| region = Guizhou & Yunnan Provinces
| country = China
| coordinates = {{coord|25.5|N|104.9|E|display=inline,title}}
| paleocoordinates = {{coord|11.7|N|94.2|E|display=inline}}
| unitof =
| subunits =
| underlies = Yangliujing Formation
| overlies = Jialingjiang Formation
| thickness =
| extent = Yunnan–Guizhou Plateau
| area =
| map = {{Location map+ | China#China Guizhou
| relief = 1
| width = 250
| float = center
| places =
{{Location map~ | China#China Guizhou
| lat_deg = 25.5
| lon_deg = 104.9
| mark = Pink ff0080 pog.svg
| marksize = 12
}}
}}
| map_caption =
}}
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,{{Cite journal |last=Fu |first=Wan-Lu |last2=Wilson |first2=George D. F. |last3=Jiang |first3=Da-Yong |last4=Sun |first4=Yuan-Lin |last5=Hao |first5=Wei-Cheng |last6=Sun |first6=Zuo-Yu |date=September 2010 |title=A New Species of Protamphisopus Nicholls (Crustacea, Isopoda, Phreatoicidea) from Middle Triassic Luoping Fauna of Yunnan Province, China |url=https://www.cambridge.org/core/journals/journal-of-paleontology/article/abs/new-species-of-protamphisopus-nicholls-crustacea-isopoda-phreatoicidea-from-middle-triassic-luoping-fauna-of-yunnan-province-china/70D2CD3E5887BCB5F3BF5631F109EBE0 |journal=Journal of Paleontology |language=en |volume=84 |issue=5 |pages=1003–1013 |doi=10.1666/10-042.1 |issn=0022-3360|url-access=subscription }} decapods,{{Cite journal |last=Feldmann |first=Rodney M. |last2=Schweitzer |first2=Carrie E. |last3=Hu |first3=Shixue |last4=Zhang |first4=Qiyue |last5=Zhou |first5=Changyoing |last6=Xie |first6=Tao |last7=Huang |first7=Jinyuan |last8=Wen |first8=Wen |date=May 2012 |title=Macrurous Decapoda from the Luoping Biota (Middle Triassic) of China |url=https://www.cambridge.org/core/journals/journal-of-paleontology/article/abs/macrurous-decapoda-from-the-luoping-biota-middle-triassic-of-china/D48074A8C2420C707124F2B6550D26B2 |journal=Journal of Paleontology |language=en |volume=86 |issue=3 |pages=425–441 |doi=10.1666/11-113.1 |issn=0022-3360|url-access=subscription }} mysidaceans and thylacocephalans{{Cite journal |last=Feldmann |first=Rodney M. |last2=Schweitzer |first2=Carrie E. |last3=Hu |first3=Shixue |last4=Huang |first4=Jinyuan |last5=Zhou |first5=Changyong |last6=Zhang |first6=Qiyue |last7=Wen |first7=Wen |last8=Xie |first8=Tao |last9=Maguire |first9=Evin |date=November 2015 |title=Spatial distribution of Crustacea and associated organisms in the Luoping Biota (Anisian, Middle Triassic), Yunnan Province, China: evidence of periodic mass kills |url=https://www.cambridge.org/core/journals/journal-of-paleontology/article/abs/spatial-distribution-of-crustacea-and-associated-organisms-in-the-luo**-biota-anisian-middle-triassic-yunnan-province-china-evidence-of-periodic-mass-kills/29B0014AFAB47DEB602033CA3EC68A82 |journal=Journal of Paleontology |language=en |volume=89 |issue=6 |pages=1022–1037 |doi=10.1017/jpa.2015.60 |issn=0022-3360|url-access=subscription }}) 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.{{Cite journal|last1=Benton|first1=Michael J.|last2=Zhang|first2=Qiyue|last3=Hu|first3=Shixue|last4=Chen|first4=Zhong-Qiang|last5=Wen|first5=Wen|last6=Liu|first6=Jun|last7=Huang|first7=Jinyuan|last8=Zhou|first8=Changyong|last9=Xie|first9=Tao|last10=Tong|first10=Jinnan|last11=Choo|first11=Brian|date=2013-10-01|title=Exceptional vertebrate biotas from the Triassic of China, and the expansion of marine ecosystems after the Permo-Triassic mass extinction|url=http://www.sciencedirect.com/science/article/pii/S0012825213001128|journal=Earth-Science Reviews|language=en|volume=125|pages=199–243|doi=10.1016/j.earscirev.2013.05.014|bibcode=2013ESRv..125..199B |issn=0012-8252|url-access=subscription}}
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.{{Cite journal |last1=Ma |first1=Zhixin |last2=Wu |first2=Huaichun |last3=Hu |first3=Shixue |last4=Fang |first4=Qiang |last5=Liu |first5=Xiting |last6=Zhou |first6=Changyong |last7=Wen |first7=Wen |last8=Zhang |first8=Qiyue |last9=Huang |first9=Jinyuan |last10=Min |first10=Xiao |date=2023-09-26 |title=Temporal duration and preservation mechanism of the Middle Triassic Luoping biota from South China constrained by geochronology and cyclostratigraphy |url=https://www.sciencedirect.com/science/article/pii/S0921818123002278 |journal=Global and Planetary Change |volume=229 |pages=104254 |doi=10.1016/j.gloplacha.2023.104254 |bibcode=2023GPC...22904254M |s2cid=263214751 |issn=0921-8181|url-access=subscription }}
Fossil content
Among others, the following fossils were reported from the formation:
=[[Ichthyopterygia]]=
=[[Sauropterygia]]=
- Altisolepis
- Austronaga{{Cite journal|last1=Wang |first1=W. |last2=Lei |first2=H. |last3=Li |first3=C. |year=2023 |title=A small-sized dinocephalosaurid archosauromorph from the Middle Triassic of Yunnan, southwestern China |journal=Vertebrata PalAsiatica |volume=62 |issue=1 |page=13 |doi=10.19615/j.cnki.2096-9899.231013 |url=http://www.vertpala.ac.cn/EN/10.19615/j.cnki.2096-9899.231013 }}
- Dawazisaurus
- Diandongichthys{{Cite journal |last1=Xu |first1=G.-H. |last2=Ma |first2=X.-Y. |year=2023 |title=A new basal ginglymodian fish (Holostei: Neopterygii) from the Middle Triassic (Anisian) Luoping Biota, Yunnan, China |journal=Zoological Journal of the Linnean Society |doi=10.1093/zoolinnean/zlad144 }}
- Diandongosaurus
- Diandongperleidus
- Dianopachysaurus
- Dianmeisaurus
- Dinocephalosaurus{{Cite journal |last1=Lu |first1=Yu-Ting |last2=Liu |first2=Jun |date=2023-10-02 |title=A new tanystropheid (Diapsida: Archosauromorpha) from the Middle Triassic of SW China and the biogeographical origin of Tanystropheidae |journal=Journal of Systematic Palaeontology |language=en |volume=21 |issue=1 |doi=10.1080/14772019.2023.2250778 |bibcode=2023JSPal..2150778L |s2cid=263634664 |issn=1477-2019}}
- Feroxichthys
- Frodoichthys
- Gimlichthys
- Gracilicollum
- Honghesaurus
- Kyphosichthys
- Luopingcoelacanthus
- Luopingosaurus{{Cite journal|last1=Xu |first1=G.-H. |last2=Shang |first2=Q.-H. |last3=Wang |first3=W. |last4=Ren |first4=Y. |last5=Lei |first5=H. |last6=Liao |first6=J.-L. |last7=Zhao |first7=L.-J. |last8=Li |first8=C. |year=2023 |title=A new long-snouted marine reptile from the Middle Triassic of China illuminates pachypleurosauroid evolution |journal=Scientific Reports |volume=13 |issue=1 |at=16 |doi=10.1038/s41598-022-24930-y | doi-access = free |pmid=36604433 |issn=2045-2322|pmc=9816097 |bibcode=2023NatSR..13...16X }}
- Luopingperleidus
- Luoxiongichthys
- Luxisaurus
- Mixosaurus
- Nothosaurus
- Panxianichthys
- Pectodens
- Platysiagum
- Pteronisculus
- Qianosuchus
- Sanchiaosaurus
- Sangiorgioichthys
- Saurichthys
- Sinosaurichthys
- Trachelosaurus
- Venusichthys
- Wumengosaurus
- Yelangichthys
- Yudaiichthys
- Yunnancoelacanthus