Picrocleidus

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Picrocleidus is an extinct genus of plesiosaur from the Middle Jurassic Oxford Clay Formation (Callovian stage) of the United Kingdom.

Discovery and naming

File:Picrocleidus beloclis.png
Life restoration

The holotype was discovered in the Oxford Clay Formation in Peterborough, England and acquired by Alfred Nicholson Leeds.[1][2] It was initially assigned to Muraenosaurus as M. beloclis by Seeley in 1892.[3] The specific name means "arrow clavicle", referring to the triangular interclavicula. M. beloclis was moved to its own genus Picrocleidus by Charles William Andrews in 1910.[2][4] The generic name is derived from Greek pikros, "sharp", en kleis, "key", again referring to the clavicles.

Five specimens are known:

The holotype specimen BMNH R1965, a postcranial skeleton.

Specimen BMNH R3698, a skeleton with skull, including a complete tail.

Specimen BMNH R2429, an old individual consisting of anterior and posterior cervical vertebrae, pectorals and the first dorsal, some dorsal ribs, the shoulder-girdle, and the left humerus.[2]

Specimen BMNH R2739, consisting of a basisphenoid and parasphenoid, cervical vertebrae, sacrals with the sacral ribs, an anterior caudal, some ventral ribs, both radii, odd paddle-bones, portions of ilia, ischia, and pubes.[1]

Specimen HM 2981666: a young individual.

Classification

Picrocleidus has previously been considered synonymous with Muraenosaurus although there are doubts in the relationship between the two groupings.[5]

Picrocleidus is currently classified as a member of the Cryptoclididae.[4]

See also

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References

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  1. a b Script error: No such module "Citation/CS1".
  2. a b c Andrews, Charles W. (1910). A descriptive catalogue of the marine reptiles of the Oxford Clay, Part 2. British Museum (Nat. Soc.) 13:139-149.
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  4. a b Muraenosaurus? Reedii, Sp. Nov. and Tricleidus? Laramiensis Knight, American Jurassic Plesiosaurs. The Journal of Geology, 20, 4, 344-352.
  5. Wilhelm BC. (2010). A New Partial Skeleton of a Cryptocleidoid Plesiosaur from the Upper Jurassic Sundance Formation of Wyoming. Journal of Vertebrate Paleontology , 30, 6, 1736-1742.

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