| Eretmosaurus | |
|---|---|
 | |
| Neotype specimen ofE. rugosus | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Superorder: | †Sauropterygia |
| Order: | †Plesiosauria |
| Superfamily: | †Plesiosauroidea |
| Family: | †Microcleididae |
| Genus: | †Eretmosaurus Seeley, 1874 |
| Type species | |
| †Plesiosaurus rugosus Owen, 1840 | |
| Other species | |
| Synonyms | |
| |
Eretmosaurus (meaning "oar lizard") is anextinctgenus ofplesiosaur from theEarly andMiddle Jurassic ofEngland andRussia.[1][2] Two species are known:E. rugosus andE. dubius.
The holotype ofE. rugosus has no known recorded specimen number[3] and it consists of vertebrae, girdles, and limb bones discovered inGranby,Nottinghamshire where theAsteroceras obtusum zone of theLower Lias Formation outcrops.[4]
SpecimenBRSMB Cb 2458 was also assigned to the species byOwen (1840).[5] This specimen later became thesyntype and it consisted of severalvertebrae that had been discovered at different locations in theBlue Lias Formation inGloucestershire acrossAust Cliff.[3]
Owen (1840) was the first to describe the specimens, which were named asPlesiosaurus rugosus.[5] Later, Owen (1865) described a headless skeleton discovered in the Ammonites stellaris zone of theBlue Lias at Granby, Nottinghamshire (NHMUK 14435) that he assigned toP. rugosus,[6] and Seeley usedNHMUK 14435 as the basis for namingEretmosaurus rugosus in 1874.[7]
AsBRSMB Cb 2458 was not diagnostic and was lost by 1940, a petition was filed with theICZN over the holotype by Brown and Bardet (1994),[1] and NHMUK 14435 was allocated as the official neotype in 1996.[8]
A fragmentary specimen ofEretmosaurus rugosus has also been identified from theMiddle Jurassic ofSiberia by Menner (1992).[2]
A partial skull and skeleton belonging to a plesiosaur was discovered in theHarpoceras faleifer zone,Whitby, England[3] and it was initially described byBlake &Tate (1876) as a species ofPlesiosaurus known asP. dubius. It was later reclassified as a species ofEretmosaurus by Blakein Blake & Tate (1876).[9]
Benton and Spencer (1995) mentioned a third species ofEretmosaurus:E. macropterus; they rectified this mistake within the same paper by mentioning on page 116 thatE. macropterus actually belongs toMicrocleidus.[4]
Eretmosaurus was classified intoRhomaleosauridae by Persson (1963),[10] then intoPliosauridae by Brown (1981),[11] then intoElasmosauridae by Bardet (1995)[12] and Bardetet al. (1999),[13] and most recently intoMicrocleididae by Bensonet al. (2012).[14]
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