Leurospondylus

Leurospondylus; Temporal range: Late Cretaceous, ; ~74–67 Ma PreꞒ Ꞓ O S D C P T J K Pg N
	Dorsal view of the holotype spine of L. ultimus
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Sauropsida
Superorder:	Sauropterygia
Order:	†Plesiosauria
Suborder:	†Plesiosauroidea
Family:	†Elasmosauridae?
Genus:	†Leurospondylus; Brown, 1913
Binomial name
	†Leurospondylus ultimus; Brown, 1913

Leurospondylus is an extinct genus of plesiosaur from the Horseshoe Canyon Formation of Canada whose family is currently disputed, but is suggested to be Elasmosauridae.^[1]

Etymology

The name Leurospondylus comes from a fusion of two Greek words, leuros (λευρός) meaning "even", "flat" or "smooth", and spondylos (σπόνδυλος) meaning "vertebra."^[1] The name of the type species L. ultimus comes from the Latin ultimus meaning "last." It was so named because this genus was the latest known occurrence of a fossil plesiosaur when it was described in 1913."^[1]

Description

Humeri (left), pelvis (middle), and coracoids (right) from the holotype

The holotype of L. ultimus was a juvenile.^[2] The fossil included 12 vertebrae but the animal is thought to have had twice that number,^[2] and was estimated to be roughly 2 meters long as a juvenile.^[2] Samuel Paul Welles noted that the vertebrae are short and similar to those of pliosaurs,^[3] while the scapulae and coracoids bear resemblance to those of elasmosaurids,^[3] thus making it difficult to determine to which family it belongs.^[3] There is some speculation that the Leurospondylus specimen is either a juvenile of a known species, or in its own, unrecognized taxonomic group.^[1]

Distribution

The holotype was found in the brackish paleoenvironment represented by the Edmonton beds located on the present-day Red Deer River. This area is part of the Horseshoe Canyon Formation in Alberta, Canada.^[1] The occurrence of this juvenile fossil in an identifiably brackish environment led to the conclusion that plesiosaurs spent their early lives in rivers and estuaries.^[1] However, some plesiosaurs spent their adult lives in fresh water also; whether Leurospondylus grew up and then left, or grew up and stayed in a fresh water ecosystem has not been determined.^[1]

References

^ ^a ^b ^c ^d ^e ^f ^g "ppne.co.uk entry on Leurospondylus". Retrieved 2008-05-20.
^ ^a ^b ^c "A new plesiosaur, Leurospondylus, from the Edmonton Cretaceous of Alberta". Bulletin of the AMNH; v. 32, article 40.
^ ^a ^b ^c Welles, S. P. 1962. A new species of elasmosaur from the Aptian of Columbia and a review of the Cretaceous plesiosaurs. University of California Publications in Geological Science 46, 96 pp.

External links

[PPNE-1] ^ ^a ^b ^c ^d ^e ^f ^g "ppne.co.uk entry on Leurospondylus". Retrieved 2008-05-20.

[brown-2] "A new plesiosaur, Leurospondylus, from the Edmonton Cretaceous of Alberta". Bulletin of the AMNH; v. 32, article 40.

[welles-3] Welles, S. P. 1962. A new species of elasmosaur from the Aptian of Columbia and a review of the Cretaceous plesiosaurs. University of California Publications in Geological Science 46, 96 pp.

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