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Steneosaurus obtusidens
''"Steneosaurus" obtusidens'' is a species of teleosaurid thalattosuchian from the Middle Jurassic Callovian of England and France. Like many other teleosaurids from Europe, it has had a convoluted taxonomic history.
==Taxonomy==
''"Steneosaurus" obtusidens'' was first described from the Callovian-aged Oxford Clay Formation of Cambridgeshire, southeastern England on the basis of a partial skeleton (NHMUK R.3168).〔Andrews, C.W. 1909. On some new Steneosaurs from the Oxford Clay of Peterborough. Annals and Magazine of Natural History 3: 299-308. http://dx.doi.org/10.1080/00222930908692579〕 Characters cited as diagnostic for ''"S." obtusidens'' included: short rostrum (preorbital length 52 percent of total skull length); teeth blunt and rounded at the tips; armor adorned with elongate pit ornamentation.
The validity of ''"Steneosaurus" obtusidens'' was disputed in a 1987 paper reviewing the type specimens of nominal teleosaurid species from the Oxford Clay. Characters used by Charles William Andrews to distinguish ''"S." obtusidens'' from other species were dismissed as variable within specimens of ''Steneosaurus edwardsi'', and ''"S." obtusidens'' was sunk as a junior synonym of ''Steneosaurus durobrivensis'' (=''S. edwardsi'').〔S. M. Adams-Tresman. 1987. The Callovian (Midde Jurassic) teleosaurid marine crocodiles from central England. Palaeontology 30(1):195-206〕 Some authors considered this taxon a probable junior synonym of ''Machimosaurus hughii'' based on a subsequently discovered specimen found in Callovian-age exposures in Calvados, Lower Normandy, France, though they stressed that a taxonomic review of blunt-snouted teleosaurids was needed.〔Hua, Vignaud, Pennetier, and Pennetier, 1994. Un squelette de Steneosaurus obtusidens Andrews, 1909 dans le Callovien de Villers-sur-mer(Calvados, France)et le problème de la definition des Teleosauridae à dents obtuses. C.R.Acad.Sci.II 318,1557–1562.〕〔Hua, S., 1999, Le Crocodilien Machimosaurus mosae (Thalattosuchia, Teleosauridae) du Kimmeridgien du Boulonnais (Pas de Calais, France): Palaeontographica Abt. A., v. 252, Lfg. 4-6, p. 141-170.〕 This synonymy was accepted in a 2009 paper regarding thalattosuchian morphometrics without comment.〔S. E. Pierce, K. D. Angielczyk, and E. J. Rayfield. 2009. Morphospace occupation in thalattosuchian crocodylomorphs: skull shape variation, species delineation and temporal patterns. Palaeontology 52(5):1057-1097〕
In 2013, a new specimen of ''Machimosaurus'' was described from Late Jurassic (Kimmeridgian deposits in southern Germany (later named ''Machimosaurus buffetauti''), and it became clear that variation within blunt-toothed teleosaurids was taxonomically significant enough for ''"Steneosaurus" obtusidens'' to be recognized as generically distinct from ''Machimosaurus''.〔Martin, J. E. and Vincent, P. (2013), New remains of Machimosaurus hugii von Meyer, 1837 (Crocodilia, Thalattosuchia) from the Kimmeridgian of Germany. Fossil Record, 16: 179–196. doi: 10.1002/mmng.201300009〕 Other cladistic and comparative studies agreed with this assessment, recovering ''"S." obtusidens'' in a clade with ''Machimosaurus'' and ''Steneosaurus edwardsi''.〔Mueller-Töwe IJ, 2005. Phylogenetic relationships of the Thalattosuchia. Zitteliana 45, 211–213.〕〔Young, M. T.; Brusatte, S. L.; De Andrade, M. B.; Desojo, J. B.; Beatty, B. L.; Steel, L.; Fernández, M. S.; Sakamoto, M.; Ruiz-Omeñaca, J. I.; Schoch, R. R. (2012). Butler, Richard J, ed. "The Cranial Osteology and Feeding Ecology of the Metriorhynchid Crocodylomorph Genera Dakosaurus and Plesiosuchus from the Late Jurassic of Europe". PLoS ONE 7 (9): e44985. doi:10.1371/journal.pone.0044985. PMC 3445579. PMID 23028723. edit〕〔Young, M. T., Hua S., Steel L., Foffa D., Brusatte S. L., Thüring S., Mateus O., Ignacio-Ruiz Omeñaca J., Lepage Y., Havilk P., & Andrade M. B. (2014). Revision of the Late Jurassic teleosaurid genus Machimosaurus (Crocodylomorpha, Thalattosuchia). Royal Society Open Science. 1(140222), 1-42.〕 As it stands, ''"Steneosaurus" obtusidens'' is clearly related to ''Machimosaurus'', but is generically distinct and in need of a new generic name.
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