Picrocleidus is an extinct genus of plesiosaur from the Middle Jurassic Oxford Clay Formation (Callovian stage) of the United Kingdom.
Discovery and naming
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
References
- ^ a b Benson, R. B. J.; Druckenmiller, P. S. (2013). "Faunal turnover of marine tetrapods during the Jurassic-Cretaceous transition". Biological Reviews. 89 (1): 1–23. doi:10.1111/brv.12038. PMID 23581455. S2CID 19710180.
- ^ 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.
- ^ Seeley, Harry G. (1892). "The nature of the shoulder girdle and clavicular arch in sauropterygia". Proceedings of the Royal Society of London. 51 (308–314): 119–151. doi:10.1098/rspl.1892.0017. ISSN 0370-1662.
- ^ a b Muraenosaurus? Reedii, Sp. Nov. and Tricleidus? Laramiensis Knight, American Jurassic Plesiosaurs. The Journal of Geology, 20, 4, 344-352.
- ^ 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.
