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 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

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

Ichthyopterygia

Ichthyosauria
GenusSpeciesMemberNotesImage
Barracudasauroides [3] B. panxianensisUpper 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. catactesUpper Member [1] A medium-sized early ichthyosaur with durophagous dentition, possibly a member of Cymbospondylidae.

Sauropterygia

Placodontiformes
GenusSpeciesMemberNotesImage
Atopodentatus [8] A. unicusUpper Member [8] A bizarre, likely herbivorous [9] sauropterygian with possible placodontiform affinities, [10] known from several well-preserved specimens.
Placodus [11] P. inexpectatusUpper Member [11] [1] A medium-sized placodontid placodont, known from a complete specimen. [11]
Saurosphargidae
GenusSpeciesMemberNotesImage
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. yunguinensisUpper Member [14] [1] A small armoured saurosphargid sauropterygian.

Related Research Articles

<i>Dinocephalosaurus</i> Extinct genus of reptiles

Dinocephalosaurus is a genus of long necked, aquatic protorosaur that inhabited the Triassic seas of China. The genus contains the type and only known species, D. orientalis, which was named by Chun Li in 2003. Unlike other long-necked protorosaurs, Dinocephalosaurus convergently evolved a long neck not through elongation of individual neck vertebrae, but through the addition of neck vertebrae that each had a moderate length. As indicated by phylogenetic analyses, it belonged in a separate lineage that also included at least its closest relative Pectodens, which was named the Dinocephalosauridae in 2021. Like tanystropheids, however, Dinocephalosaurus probably used its long neck to hunt, utilizing the fang-like teeth of its jaws to ensnare prey; proposals that it employed suction feeding have not been universally accepted. It was probably a marine animal by necessity, as suggested by the poorly-ossified and paddle-like limbs which would have prevented it from going ashore.

<span class="mw-page-title-main">Thalattosauria</span> Extinct order of sea reptiles

Thalattosauria is an extinct order of prehistoric marine reptiles that lived in the Middle to Late Triassic. Thalattosaurs were diverse in size and shape, and are divided into two superfamilies: Askeptosauroidea and Thalattosauroidea. Askeptosauroids were endemic to the Tethys Ocean, their fossils have been found in Europe and China, and they were likely semiaquatic fish eaters with straight snouts and decent terrestrial abilities. Thalattosauroids were more specialized for aquatic life and most had unusual downturned snouts and crushing dentition. Thalattosauroids lived along the coasts of both Panthalassa and the Tethys Ocean, and were most diverse in China and western North America. The largest species of thalattosaurs grew to over 4 meters (13 feet) in length, including a long, flattened tail utilized in underwater propulsion. Although thalattosaurs bore a superficial resemblance to lizards, their exact relationships are unresolved. They are widely accepted as diapsids, but experts have variously placed them on the reptile family tree among Lepidosauromorpha, Archosauromorpha, ichthyosaurs, and/or other marine reptiles.

<i>Macrocnemus</i> Extinct genus of reptiles

Macrocnemus is an extinct genus of archosauromorph reptile known from the Middle Triassic of Europe and China. Macrocnemus is a member of the Tanystropheidae family and includes three species. Macrocnemus bassanii, the first species to be named and described, is known from the Besano Formation and adjacent paleontological sites in the Italian and Swiss Alps. Macrocnemus fuyuanensis, on the other hand, is known from the Zhuganpo Formation in southern China. A third species, Macrocnemus obristi, is known from the Prosanto Formation of Switzerland and is characterized by gracile limbs. The name Macrocnemus is Greek for "long tibia".

<i>Helveticosaurus</i> Extinct genus of reptiles

Helveticosaurus is an extinct genus of diapsid marine reptile known from the Middle Triassic of southern Switzerland. It contains a single species, Helveticosaurus zollingeri, known from the nearly complete holotype T 4352 collected at Cava Tre Fontane of Monte San Giorgio, an area well known for its rich record of marine life during the Middle Triassic.

<i>Sinosaurosphargis</i> Extinct genus of reptiles

Sinosaurosphargis is an extinct genus of basal marine saurosphargid reptile known from the Middle Triassic Guanling Formation of Yunnan and Guizhou Provinces, southwestern China. It contains a single species, Sinosaurosphargis yunguiensis.

<i>Wumengosaurus</i> Extinct genus of reptiles

Wumengosaurus is an extinct aquatic reptile from the Middle Triassic Guanling Formation of Guizhou, southwestern China. It was originally described as a basal eosauropterygian and usually is recovered as such by phylogenetic analyses, although one phylogeny has placed it as the sister taxon to Ichthyosauromorpha while refraining from a formal re-positioning. It was a relatively small reptile, measuring 95.5–130.5 cm (3.13–4.28 ft) in total body length.

Largocephalosaurus is an extinct genus of basal saurosphargid, a marine reptile known from the Middle Triassic Guanling Formation of Yunnan and Guizhou Provinces, southwestern China. It contains a type species, Largocephalosaurus polycarpon, and a second species L. qianensis.

Eohupehsuchus is a genus of extinct aquatic diapsid from the Upper Spathian of Hubei Province, located in Central China. The genus is monotypic and belongs to the order Hupehsuchia, whose members are characterized by toothless beak-like snouts, a row of dermal plates along their backs, and aquatic adaptations including paddle-shaped limbs and fusiform bodies with pachyostotic ribs.

Eretmorhipis is an extinct genus of hupehsuchian marine reptiles from the Early Triassic of China. It is currently known from two specimens that were discovered in an exposure of the Jialingjiang Formation in Yuan'an County, Hubei, and referred to the newly named species Eretmorhipis carrolldongi in 2015.

Wangosaurus is an extinct genus of basal pistosauroid known from the Middle Triassic Falang Formation of Xingyi in Guizhou Province, southwestern China. It contains a single species, Wangosaurus brevirostris, first described and named by Le-Tian Ma, Da-Yong Jiang, Olivier Rieppel, Ryosuke Motani and Andrea Tintori in 2015. The specific name brevirostris comes from Greek for "short snout". It is known solely from its holotype, a nearly complete and articulated skeleton measuring 2.2 m (7.2 ft) long.

<span class="mw-page-title-main">Saurosphargidae</span> Extinct family of reptiles

Saurosphargidae is an extinct family of marine reptiles known from the Early Triassic and early Middle Triassic of Europe and China.

Saurosphargis is an extinct genus of a basal marine reptile, saurosphargid, known from the Middle Triassic of southwestern Poland and eastern Netherlands. It contains a single species, Saurosphargis volzi.

<i>Eusaurosphargis</i> Extinct genus of reptiles

Eusaurosphargis is an extinct genus of a diapsid reptile, known from the Middle Triassic Besano Formation of northern Italy and Prosanto Formation of south-eastern Switzerland. It contains a single species, Eusaurosphargis dalsassoi. It was a small reptile, measuring 20 cm (7.9 in) long.

The Xiaowa Formation is a Carnian-age geological formation found in southern China. It is a sequence of limestone and marls from the Carnian stage of the Triassic. Its lower section was previously known as the Wayao Formation or Wayao Member of the Falang Formation. In 2002, the Wayao Member was renamed and raised to the Xiaowa Formation to prevent confusion with an Eocene unit of the same name. Crinoids and marine reptiles are abundant in the Xiaowa Formation, forming a lagerstätte known as the Guanling biota. Ammonoids and conodonts found in the formation constrain its age to the early Carnian. Reptiles of the Guanling biota include ichthyosaurs, thalattosaurs, placodonts, and Odontochelys. Sedimentary events within this formation have been tied to the Carnian Pluvial Event.

The Zhuganpo Formation is a Triassic geologic unit found in southern China. It has historically been known as the Zhuganpo Member of the Falang Formation. A diverse fossil assemblage known as the Xingyi biota or Xingyi Fauna can be found in the upper part of the Zhuganpo Formation. Fossils of the Xingyi biota include articulated skeletons of marine reptiles, abundant fish, and a plentiful assortment of invertebrates indicating a Ladinian to Carnian age for the sediments of the formation.

Panzhousaurus is an extinct genus of pachypleurosaur from the Middle Triassic of China. The type species is P. rotundirostris. The preserved portion of the holotype measures 36 cm (14 in) long, and its total body length may have been less than 50 cm (20 in).

This list of fossil reptiles described in 2014 is a list of new taxa of fossil reptiles that were described during the year 2014, as well as other significant discoveries and events related to reptile paleontology that occurred in 2014.

<i>Luopingosaurus</i> Extinct genus of sauropterygian reptiles

Luopingosaurus is an extinct genus of pachypleurosaurid sauropterygian from the Middle Triassic Guanling Formation of Yunnan Province, China. The genus contains a single species, L. imparilis, known from a well-preserved, nearly complete skeleton.

References

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