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[dinosaur] New Wahlisaurus specimen from England + Ophthalmosaurus from Russia





Ben Creisler
bcreisler@gmail.com


Two new ichthyosaur papers:


Dean R. Lomax, Mark Evans and Simon Carpenter (2018)
An ichthyosaur from the UK TriassicâJurassic boundary: A second specimen of the leptonectid ichthyosaur Wahlisaurus massarae Lomax 2016
Geological Journal (advance online publication)
DOI: 10.1002/gj.3155
http://onlinelibrary.wiley.com/doi/10.1002/gj.3155/full



The holotype of Wahlisaurus massarae is known only from a partial skull and postcranial skeleton from the Lower Jurassic, collected near Normanton on Soar, Nottinghamshire, UK. It is diagnosed relative to other ichthyosaurs on the basis of autapomorphies of the coracoid and a unique combination of characters. Here, we report a second specimen of W. massarae. The new specimen comprises a practically complete right coracoid that clearly shows the unique morphology of W. massarae. This specimen was collected in situ from a quarry in Somerset, from the base of the Blue Lias Formation, which corresponds to the TriassicâJurassic boundary (uppermost Rhaetian or lowermost Hettangian), extending the geographic and stratigraphic range of the species. Furthermore, the coracoid of the new specimen is 20% anteroposteriorly longer than in the holotype, representing a larger individual. In light of preparation and the identification of additional fragments of the holotype, a redescription of the skull morphology of the holotype, as well as comparison with the skull roof of Leptonectes tenuirostris, is included.


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Available only in Russian for now (English translation version not out yet):


M.S Arkhangelsky, N.G. Zverkov, O.S. Spasskaya & A.V. Evgrafov (2018)
On the First Reliable Find of Ichthyosaur Ophthalmosaurus icenicus Seeley from the Oxfordian-Kimmeridgian of European Russia.
Paleontological Journal 2018(1): 45-52
DOI: 10.7868/S0031031X18010099Â
https://elibrary.ru/item.asp?id=32290536


Here we describe incomplete skeleton of ichthyosaur Ophthalmosaurus icenicus Seeley, 1874, excavated from the Oxfordian-Kimmeridgian deposits near Sysran (Samara Region). The majority of features, characteristic of the genus Ophthalmosaurus, are expressed in the described specimen: basioccipital with reduced extracondylar area, still present ventrally and laterally, bear prominent ventral notch, and is largely occupied laterally by an extensive pair of stapedial facets; flattened scapular shaft; humerus with three distal facets, the anterior, smallest one, articulating with a preaxial accessory element, is tapered; distally faced radial facet and posterodistally faced ulnar facet; concave and edgy posterior surface of the ulna, involved in perichondral ossification; rhomboid intermedium with two equal distal facets for the second and third distal carpals; rounded and thick, loosely arranged mesopodial and autopodial elements. This is the first reliable occurrence of Ophthalmosaurus in the Oxfordian-Kimmeridgian of Russia. Previously described Kimmeridgian O. undorensis Efimov, 1991, based on indeterminate material, could be only referred to as Ophthalmosauridae indet.




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