Eretmosaurus

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Eretmosaurus
Temporal range: Early - Middle Jurassic, 199.5–161.5  Ma
Eretmosaurus rugosus.JPG
Neotype specimen of E. rugosus
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Superorder:† Sauropterygia
Order:† Plesiosauria
Superfamily:† Plesiosauroidea
Family:† Microcleididae
Genus:† Eretmosaurus
Seeley, 1874
Type species
†Eretmosaurus rugosus
Seeley, 1874
Other species
Synonyms

Eretmosaurus (meaning "oar lizard") is an extinct genus of plesiosaur from the Early and Middle Jurassic of England and Russia. [1] [2] Two species are known: E. rugosus and E. dubius.

Contents

History

Eretmosaurus rugosus

c. 1870 illustration of the neotype of E. rugosus Eretmosaurus.jpg
c. 1870 illustration of the neotype of E. rugosus
Restoration of E. rugosus Eretmosaurus rugosus.png
Restoration of E. rugosus

The holotype of E. rugosus has no known recorded specimen number [3] and it consists of vertebrae, girdles, and limb bones discovered in Granby, Nottinghamshire where the Asteroceras obtusum zone of the Lower Lias Formation outcrops. [4]

Specimen BRSMB Cb 2458 was also assigned to the species by Owen (1840). [5] This specimen later became the syntype and it consisted of several vertebrae that had been discovered at different locations in the Blue Lias Formation in Gloucestershire across Aust Cliff. [3]

Owen (1840) was the first to describe the specimens, which were named as Plesiosaurus rugosus. [5] Later, Owen (1865) described a headless skeleton discovered in the Ammonites stellaris zone of the Blue Lias at Granby, Nottinghamshire (NHMUK 14435) that he assigned to P. rugosus, [6] and Seeley used NHMUK 14435 as the basis for naming Eretmosaurus rugosus in 1874. [7]

As BRSMB Cb 2458 was not diagnostic and was lost by 1940, a petition was filed with the ICZN over the holotype by Brown and Bardet (1994), [1] and NHMUK 14435 was allocated as the official neotype in 1996. [8]

A fragmentary specimen of Eretmosaurus rugosus has also been identified from the Middle Jurassic of Siberia by Menner (1992). [2]

Eretmosaurus dubius

A partial skull and skeleton belonging to a plesiosaur was discovered in the Harpoceras faleifer zone, Whitby, England [3] and it was initially described by Blake & Tate (1876) as a species of Plesiosaurus known as P. dubius. It was later reclassified as a species of Eretmosaurus by Blake in Blake & Tate (1876). [9]

Other species

Benton and Spencer (1995) mentioned a third species of Eretmosaurus: E. macropterus; they rectified this mistake within the same paper by mentioning on page 116 that E. macropterus actually belongs to Microcleidus . [4]

Classification

Eretmosaurus was classified into Rhomaleosauridae by Persson (1963), [10] then into Pliosauridae by Brown (1981), [11] then into Elasmosauridae by Bardet (1995) [12] and Bardet et al. (1999), [13] and most recently into Microcleididae by Benson et al. (2012). [14]

See also

References

  1. 1 2 David S. Brown and Nathalie Bardet (1994). Plesiosaurus rugosus Owen, 1840 (currently Eretmosaurus rugosus, Reptilia, Plesiosauria) proposed designation of a neotype. Bulletin of Zoological Nomenclature 51(3)
  2. 1 2 Menner, V. V. (1992). "Remains of Plesiosaurs from Middle Jurassic Deposits of Eastern Siberia". Russian Academy of Sciences, Department of Geology, Geophysics, Geochemistry and Mining Sciences, Order of the Red Manner of Labour Geological Institute: 74–91.
  3. 1 2 3 "Eretmosaurus". Paleofile. Retrieved 18 September 2025.
  4. 1 2 Benton, M. J. and Spencer, P. S. (1995). Fossil reptiles of Great Britain. Chapman and Hall, London, 386 pp.
  5. 1 2 R. Owen. (1840). Report on British fossil reptiles. Report of the Ninth Meeting of the British Association for the Advancement of Science, Reports on the State of Science 43-126
  6. ↑ R. Owen. (1865). A monograph of the fossil Reptilia of the Liassic formations. Part I, Sauropterygia. Palaeontographical Society Monographs 17(75):1-40
  7. ↑ Seeley, H. G., (1874), Note on some of the generic modifications of the plesiosaurian pectoral arch: Quarterly Journal of the Geological Society of London, 1874, p. 436-449.
  8. ↑ David S. Brown and Nathalie Bardet (1996). Plesiosaurus rugosus Owen, 1840 (currently Eretmosaurus rugosus, Reptilia, Plesiosauria) neotype designated. Bulletin of Zoological Nomenclature 53(1)
  9. ↑ Blake, John F.; Tate, Ralph (1876). The Yorkshire Lias. University of California. ISBN   978-93-331-6341-5.{{cite book}}: ISBN / Date incompatibility (help)
  10. ↑ Persson, P.O. (1963): A revision of the classification of the Plesiosauria, with a synopsis of the stratigraphical and geographical distribution of the group. University of Lunds Årsskrift 59, No. 1, p. 1-57.
  11. ↑ Brown, D. S. (1981). The English Upper Jurassic Plesiosauroidea (Reptilia) and a review of the phylogeny and classification of the Plesiosauria. Bulletin of the British Museum (Natural History): Geology, 35, (4), 253-347.
  12. ↑ Bardet, N. (1995). Evolution et extinction des reptiles marins au cours du Mésozoïque. Palaeovertebrata, 24, 177-283.
  13. ↑ Bardet, N.; Godefroit, P.; and Sciau, J. (1999). A new elasmosaurid plesiosaur from the Lower Jurassic of Southern France. Palaeontology'", 42, (5), 927-952.
  14. ↑ Benson, Roger B. J.; Evans, Mark; Druckenmiller, Patrick S. (2012-03-16). Lalueza-Fox, Carles (ed.). "High Diversity, Low Disparity and Small Body Size in Plesiosaurs (Reptilia, Sauropterygia) from the Triassic–Jurassic Boundary". PLOS ONE. 7 (3) e31838. Bibcode:2012PLoSO...731838B. doi: 10.1371/journal.pone.0031838 . ISSN   1932-6203. PMC   3306369 . PMID   22438869.
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