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Nothosaur

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Extinct order of reptiles

Nothosauroidea
Temporal range: Early-Late Triassic, 251–210 Ma PreꞒ O S D C P T J K Pg N Possible late Rhaetian record.
Nothosaurus
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Superorder: Sauropterygia
Clade: Eosauropterygia
Order: Nothosauroidea
Baur, 1889
Subgroups

Nothosaurs (superfamily Nothosauroidea) were Triassic marine sauropterygian reptiles. They averaged about 3 metres (10 ft) in length, with a long body and tail. The feet were paddle-like, and are known to have been webbed in life, to help power the animal when swimming. The neck was quite long, and the head was elongated and flattened, and relatively small in relation to the body. The margins of the long jaws were equipped with numerous sharp outward-pointing teeth, indicating a diet of fish and squid.

Taxonomy

The Nothosauroidea has been suggested to consist of two suborders, the Pachypleurosauria, which are small primitive forms, and the Nothosauria (including two families Nothosauridae and Simosauridae), which may have evolved from pachypleurosaurs.

The relation of pachypleurosaurs to Nothosauroidea is uncertain, as several analyses recover the clade as basal to Eusauropterygia, e.i. the clade formed by Nothosauria and Pistosauroidea, instead as the sister taxon of Nothosauria. Many recent analyses have recovered the pachypleurosaurs as a basal clade of eosauropterygians outside of the nothosauroidea.

Nothosaur-like reptiles were in turn ancestral to the more completely marine plesiosaurs, which replaced them at the end of the Triassic period.

In their 2024 description of Dianmeisaurus mutaensis, Hu, Li & Liu recovered the Nothosauroidea as the sister taxon to the Pachypleurosauria. The results of their phylogenetic analyses are shown in the cladogram below:

Sauropterygia

Placodus

Eosauropterygia

Pistosauridae

Majiashanosaurus

Hanosaurus

Nothosauroidea

Pachypleurosauria

Distribution

A 2024 description of a fossil nothosaur vertebra from the Anisian of New Zealand indicates that nothosaurs dispersed worldwide from their region of origin in the northern Tethys much earlier than presumed, eventually reaching the southern polar region of Panthalassa by the Middle Triassic. This vertebra is the oldest sauropterygian fossil from the Southern Hemisphere, and appears to be from a taxon related to Nothosaurus and Lariosaurus.

References

  1. F. v. Huene. 1956. Paläontologie und Phylogenie der Niederen Tetrapoden . VEB Gustav Fischer Verlang, Jena 1-716
  2. Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 72. ISBN 978-1-84028-152-1.
  3. Olivier Rieppel (1999). "The sauropterygian genera Chinchenia, Kwangsisaurus, and Sanchiaosaurus from the Lower and Middle Triassic of China". Journal of Vertebrate Paleontology. 19 (2): 321–337. Bibcode:1999JVPal..19..321R. doi:10.1080/02724634.1999.10011144.
  4. 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.
  5. ^ Hu, Yi-Wei; Li, Qiang; Liu, Jun (2024-01-05). "A new pachypleurosaur (Reptilia: Sauropterygia) from the Middle Triassic of southwestern China and its phylogenetic and biogeographic implications". Swiss Journal of Palaeontology. 143 (1): 1. doi:10.1186/s13358-023-00292-4. ISSN 1664-2384.
  6. Kear, Benjamin P.; Roberts, Aubrey J.; Young, George; Terezow, Marianna; Mantle, Daniel J.; Barros, Isaias Santos; Hurum, Jørn H. (2024). "Oldest southern sauropterygian reveals early marine reptile globalization". Current Biology. 34 (12): R562 – R563. doi:10.1016/j.cub.2024.03.035. ISSN 0960-9822.

Sources

Sauropterygia
Sauropsida
Sauropterygia
    • see below↓
Sauropterygia
Sauropterygia
Helveticosauridae?
Saurosphargidae
Placodontia
Cyamodontoidea
Eosauropterygia
    • see below↓
Helveticosaurus zollingeri Placochelys placodonta
Eosauropterygia
Eosauropterygia
Pachypleurosauria
Nothosauroidea
Simosauridae
Nothosauridae
Pistosauroidea
Plesiosauria
    • see below↓
Keichousaurus hui

Nothosaurus mirabilis

Pistosaurus longaevus
Plesiosauria
Plesiosauria
Rhomaleosauridae
Pliosauridae
Thalassophonea
Brachaucheninae
Plesiosauroidea
Microcleididae
Cryptoclidia
    • see below↓
Macroplata tenuiceps

Attenborosaurus conybeari

Hydrorion brachypterygius
Cryptoclidia
Cryptoclididae
Colymbosaurinae
Cryptoclidinae
Muraenosaurinae
Xenopsaria
Leptocleidia
Leptocleididae
Polycotylidae
Palmulasaurinae
Occultonectia
Polycotylinae
Dolichorhynchia
Elasmosauridae
Euelasmosaurida
Elasmosaurinae
Weddellonectia
Aristonectinae
Cryptoclidus eurymerus

Leptocleidus capensis

Elasmosaurus platyurus
Taxon identifiers
Nothosauria


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