Clevosaurus

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Clevosaurus
Temporal range: Late Triassic - Early Jurassic Carnian–Sinemurian
Clevosaurus.svg
Skulls of C. hudsoni (left) and C. cambrica (right)
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Rhynchocephalia
Family: Clevosauridae
Genus: Clevosaurus
Swinton, 1939
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

Clevosaurus (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] Five species of Clevosaurus have been found in ancient fissure fill deposits in south-west England and Wales, alongside other sphenodontians, early mammals and dinosaurs. In regards to its Pangaean distribution, C. hadroprodon is the oldest record of a sphenodontian from Gondwana.[5]

Reconstructions of the skulls of C. hudsoni (A) and C. cambrica (B), reconstructed areas in orange.

History of discovery[]

The first species of Clevosaurus to be described was C. hudsoni, which was described by William Elgin Swinton in 1939 from a fissure fill deposit in Cromhall Quarry (Magnesian Conglomerate Formation) in the county of Gloucestershire, England, with the name of the county lending its name to the genus.[6]

Description[]

Skull of Clevosaurus brasiliensis

The teeth of Clevosaurus species are elongated and occlude precisely with the opposite pair of teeth, leaving conspicuous wear facets and acting as a self-sharpening cutting surface.[7]

Paleobiology[]

Life restoration of Clevosaurus hadroprodon

Species of Clevosaurus were likely insectivorous. Biomechanical modelling suggests that they had high enough tooth pressures and strong enough bite force to crush chitin, indicating that they had the ability to feed on thick-shelled beetles as well as possibly small vertebrates.[7]

List of species[]

  • †Clevosaurus bairdi Sues et al. 1994 McCoy Brook Formation, Canada, Hettangian
  • †Clevosaurus brasiliensis Bonaparte and Sues 2006[8] 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[9] 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 now considered indeterminate within the genus.[10] 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):[11]

 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.[11] It was subsequently assigned to a new genus, Fraserosphenodon, in 2018.[12]

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". 19 August 2019.
  4. ^ a b 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. ^ "A new sphenodontian from Brazil is the oldest record of the group in Gondwana". phys.org (in American English). Retrieved 2019-08-15.
  6. ^ W. E. Swinton. (1939). A new Triassic rhynchocephalian from Gloucestershire. Annals and Magazine of Natural History: Zoology, Botany, and Geology 4:591-594
  7. ^ a b 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. S2CID 220902843.
  8. ^ 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.
  9. ^ 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.
  10. ^ Jones MEH. 2006 The Early Jurassic clevosaurs from China (Diapsida: Lepidosauria). New Mex. Museum Nat. Hist. Sci. Bull. 37, 548–562.
  11. ^ a b 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. Bibcode:2015PLoSO..1037523H. doi:10.1371/journal.pone.0137523. PMC 4565693. PMID 26355294.
  12. ^ 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.
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