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 speciesL. ultimus comes from the Latinultimus 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 individual vertebrae of the holotype
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]
^ abc"A new plesiosaur, Leurospondylus, from the Edmonton Cretaceous of Alberta". Bulletin of the AMNH; v. 32, article 40.
^ abcWelles, 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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