Clevosaurus

Clevosaurus (CLEE-vo-SORE-us) (meaning "Gloucester lizard") is an extinct genus of rhynchocephalian reptile from the Late Triassic and the Early Jurassic periods.[3] Species of Clevosaurus were widespread across Pangaea, and have been found on all continents except Australia and Antarctica.[4] The teeth of Clevosaurus had a shearing function, and they had a strong enough bite force to crush chitin.[5] Fossils of Clevosaurus, as well as other sphenodontians, early mammals and dinosaurs have been found in ancient fissure fill deposits in south-west England and Wales. In regards to its Pangaean distribution, C. hadroprodon is the oldest record of a sphenodontian from Gondwana.[6]

Clevosaurus Temporal range: Late Triassic - Early Jurassic Carnian–Sinemurian PreꞒ Ꞓ O S D C P T J K Pg N
Skulls of C. brasiliensis
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Rhynchocephalia
Family:	Clevosauridae
Genus:	Clevosaurus Swinton, 1939
Named Species
C. bairdi Sues, Shubin, & Olson, 1994 C. brasiliensis Bonaparte & Sues, 2006 C. cambrica Keeble, Whiteside & Benton, 2018[1] C. convallis Säilä, 2005[2] C. hadroprodon Hsiou et al. 2019 C. hudsoni Swinton, 1939 (type) C. mcgilli Wu, 1994 C. minor Fraser & Walkden, 1983 C. petilus (Young, 1982) C. sectumsempra Bonaparte, 2006 C. wangi Wu, 1994
Synonyms
Dianosaurus Young, 1982

List of species

• †Clevosaurus bairdi Sues et al. 1994 McCoy Brook Formation, Canada, Hettangian
• †Clevosaurus brasiliensis Bonaparte and Sues 2006[7] Caturrita Formation, Brazil, Norian
• †Clevosaurus cambrica Keeble et al. 2018 Pant-y-ffynnon Quarry fissure fill, Wales, Rhaetian
• †Clevosaurus convallis Saila 2005 St. Bride's Island fissure fill, Wales, Hettangian
• †Clevosaurus hadroprodon Hsiou et al. 2019 Santa Maria Formation, Brazil, Carnian
• †Clevosaurus hudsoni Swinton 1939 Cromhall Quarry fissure fill, England, Rhaetian
• †Clevosaurus minor Fraser 1988 Cromhall Quarry fissure fill, England, Rhaetian
• †Clevosaurus sectumsemper Klein et al. 2015[8] Woodleaze Quarry fissure fill, England, Rhaetian

The three species known from the Sinemurian aged Lufeng Formation of China (C. mcgilli, C.wangi and C. petilus) are considered indeterminate within the genus.[9] Indeterminate remains are also known from the Stormberg Group (either Elliot or Clarens Formation) of South Africa, dating to the Hettangian.[4]

Species

Below is a cladogram of the relationships within Clevosauridae based on the phylogenetic analysis of Hsiou et al. (2015):[10]

Clevosauridae	Polysphenodon mulleri       Brachyrhinodon taylori     Clevosaurus sp. (South Africa)     Clevosaurus convallis     Clevosaurus hudsoni     Clevosaurus petilus       Clevosaurus bairdi     Clevosaurus mcgilli       Clevosaurus wangi     Clevosaurus brasiliensis     Clevosaurus cambrica

"Clevosaurus" latidens was recovered outside of Clevosauridae, as the sister taxon of Opisthodontia.[10] It was subsequently assigned to a new genus, Fraserosphenodon, in 2018.[11]

Notes

1. Emily Keeble; David I. Whiteside; Michael J. Benton (2018). "The terrestrial fauna of the Late Triassic Pant-y-ffynnon Quarry fissures, South Wales, UK and a new species of Clevosaurus (Lepidosauria: Rhynchocephalia)". Proceedings of the Geologists' Association. in press (2): 99–119. doi:10.1016/j.pgeola.2017.11.001. hdl:1983/5afdc677-3ea0-4519-813d-6052ef8370ec.
2. Säilä, Laura K. (2005). "A new species of the sphenodontian reptile Clevosaurus from the Lower Jurassic of South Wales". Palaeontology. 48 (4): 817–831. doi:10.1111/j.1475-4983.2005.00486.x.
3. "A New Clevosaurid from the Triassic (Carnian) of Brazil and the Rise of Sphenodontians in Gondwana".
4. Sues, H. D.; Reisz, R. (1995). "First record of the early mesozoic sphenodontian clevosaurus (lepidosauria: rhynchocephalia) from the southern hemisphere". Journal of Paleontology. 69 (1): 123–126. doi:10.1017/s0022336000026974.
5. Chambi‐Trowell, Sofia A. V.; Whiteside, David I.; Benton, Michael J.; Rayfield, Emily J. (16 June 2020). Lautenschlager, Stephan (ed.). "Biomechanical properties of the jaws of two species of Clevosaurus and a reanalysis of rhynchocephalian dentary morphospace". Palaeontology. 63 (6): 919–939. doi:10.1111/pala.12493. ISSN 0031-0239.
6. "A new sphenodontian from Brazil is the oldest record of the group in Gondwana". phys.org. Retrieved 2019-08-15.
7. Bonaparte, J. F.; Sues, H. D. (2006). "A new species of clevosaurus (lepidosauria: rhynchocephalia) from the upper Triassic of Rio Grande do Sul, Brazil". Palaeontology. 49 (1): 917–923. doi:10.1111/j.1475-4983.2006.00568.x.
8. Klein, Catherine G.; Whiteside, David I.; de Lucas, Victor Selles; Viegas, Pedro A.; Benton, Michael J. (2015). "A distinctive Late Triassic microvertebrate fissure fauna and a new species of Clevosaurus (Lepidosauria: Rhynchocephalia) from Woodleaze Quarry, Gloucestershire, UK". Proceedings of the Geologists' Association. 126 (3): 402–416. doi:10.1016/j.pgeola.2015.05.003.
9. Jones MEH. 2006 The Early Jurassic clevosaurs from China (Diapsida: Lepidosauria). New Mex. Museum Nat. Hist. Sci. Bull. 37, 548–562.
10. Annie Schmaltz Hsiou; Marco Aurélio Gallo De França; Jorge Ferigolo (2015). "New Data on the Clevosaurus (Sphenodontia: Clevosauridae) from the Upper Triassic of Southern Brazil". PLoS ONE. 10 (9): e0137523. doi:10.1371/journal.pone.0137523. PMC 4565693. PMID 26355294.
11. Jorge A. Herrera-Flores; Thomas L. Stubbs; Armin Elsler; Michael J. Benton (2018). "Taxonomic reassessment of Clevosaurus latidens Fraser, 1993 (Lepidosauria, Rhynchocephalia) and rhynchocephalian phylogeny based on parsimony and Bayesian inference". Journal of Paleontology. Online edition (4): 734–742. doi:10.1017/jpa.2017.136.

References

• Paleofile
• Gill PG, Säilä LK, Corfe IJ, Challands TJ, Williams M, Clemens WA (2006). The fauna and palaeoenvironment of St. Brides Island: Evidence from the lower Jurassic fissure fills of South Wales. In Barrett PM, Evans SE (eds.). Ninth international symposium on Mesozoic terrestrial ecosystems and biota. pp 48−51. London: Natural History Museum.
• Jones MEH (2006) The Early Jurassic clevosaurs from China (Diapsida: Lepidosauria). Natl Mus Nat Hist Sci Bull, 37:548–562.
• Jones MEH (2009). Dentary tooth shape in Sphenodon and its fossil relatives (Diapsida: Lepidosauria: Rhynchocephalia). In Koppe T, Meyer G, Alt KW, (eds). Interdisciplinary Dental Morphology, Frontiers of Oral Biology (vol 13). Greifswald, Germany; Karger. 9–15.