Thalattosauroidea

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Thalattosauroidea
Temporal range: Middle To Late Triassic, 247.2–215  Ma
Thalattosauridae.jpg
Life restoration of Nectosaurus halinus (right) and Thalattosaurus alexandrae (left)
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Thalattosauria
Superfamily: Thalattosauroidea
Merriam, 1904
Subtaxa
Synonyms

Thalattosauroidea is a superfamily of thalattosaurs, a Triassic group of marine reptiles. It was named in 1904 by paleontologist John Campbell Merriam to include the genus Thalattosaurus from California. Thalattosauroids are one of two groups of Thalattosauria, the other being Askeptosauroidea. Thalattosauroids make up the "traditional" thalattosaurs with large downturned snouts, short necks, and long, paddle-like tails.

Classification

Thalattosauria includes North American genera such as Thalattosaurus and Nectosaurus as well as recently described Chinese forms such as Xinpusaurus . A 1999 study of thalattosaurs, which established much of the currently accepted phylogeny of the group, referred to Thalattosauroidea as Thalattosauria, while calling the larger group Thalattosauriformes. More recent phylogenetic studies have come upon the same conclusions, but refer to the group as Thalattosauroidea in order to contrast it with another superfamily of thalattosaurs, Askeptosauroidea. [1] [2] Below is a cladogram from Wu et al. (2009) showing the phylogenetic relationships of Thalattosauroidea: [3]

Thalattosauria

Askeptosauroidea

 Thalattosauroidea 

Nectosaurus

Xinpusaurus

Kössen-Form

Agkistrognathus

Paralonectes

Thalattosaurus

  Claraziidae  

Clarazia

Hescheleria

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

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<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 period. 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.

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

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

Xinpusaurus is an extinct genus of thalattosaur from the Late Triassic of Guanling in Guizhou, China. Several species have been named since 2000: the type species X. suni along with the species X. bamaolinensis and X. kohi. A 2013 study proposed that all three species are synonymous with each other, in which case X. suni would be the only valid species, although a 2014 study argued that X. kohi was also valid. A fourth species, X. xingyiensis, was described in 2016.

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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.

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

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

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.

References

  1. Rieppel, O.; Liu, J.; Bucher, H. (2000). "The first record of a thalattosaur reptile from the Late Triassic of southern China (Guizhou Province, PR China)". Journal of Vertebrate Paleontology. 20 (3): 507–514. doi:10.1671/0272-4634(2000)020[0507:TFROAT]2.0.CO;2. S2CID   140706921.
  2. Liu, J.; Rieppel, O. (2005). "Restudy of Anshunsaurus huangguoshuensis (Reptilia: Thalattosauria) from the Middle Triassic of Guizhou, China" (PDF). American Museum Novitates (3488): 1–34. doi:10.1206/0003-0082(2005)488[0001:roahrt]2.0.co;2. ISSN   0003-0082. S2CID   55642315.
  3. Wu, X.-C.; Cheng, Y.-N.; Sato, T.; Shan, H.-Y. (2009). "Miodentosaurus brevis Cheng et al., 2007 (Diapsida: Thalattosauria): its postcranial skeleton and phylogenetic relationships" (PDF). Vertebrata PalAsiatica. 47 (1): 1–20.