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Helveticosaurus
''Helveticosaurus'' is an extinct genus of diapsid marine reptile known from the Middle Triassic (Anisian-Ladinian boundary) of southern Switzerland. It contains a single species, ''Helveticosaurus zollingeri'', known from the nearly complete holotype T 4352 collected at Cava Tre Fontane of Monte San Giorgio, an area well known for its rich record of marine life during the Middle Triassic.
==Description and paleobiology==
''Helveticosaurus'' is known from a nearly complete holotype which includes the premaxilla, maxilla, prefrontal, postfrontal, postorbital, squamosal, dentary and a poscranial skeleton. Several disarticulated elements are also known including teeth, portions of the snout and poscranial elements.〔 ''Helveticosaurus'' is about 2 meters long from snout to tail.〔http://palaeos.com/vertebrates/archosauromorpha/helveticosauridae.html〕 It possessed many features that were adaptations to a marine lifestyle in the shallow-sea environment that existed in Europe at the time when much of the continent was part of the Tethys Ocean. The long, flexible tail is similar to what can be seen in other extinct marine reptiles such as thalattosaurs, and it probably propelled itself through the water by means of lateral undulation. However, ''Helveticosaurus'' also possessed a robust pectoral girdle and forelimbs that were well adapted for paddle like propulsion as a supplementary method of locomotion, as seen in secondarily aquatic tetrapods. This unique combination of undulation and paddling is highly unusual for an aquatic reptile.
The caniniform teeth suggest a predatory lifestyle for ''Helveticosaurus''. Unlike most other marine reptiles which exhibited a lengthening and narrowing of the skull, the head of ''Helveticosaurus'' was more robust and boxlike. It is unknown what purpose the shortness of the skull would have had in feeding.〔Naish, D. (2008). "One of so many bizarre Triassic marine reptiles." Weblog entry. ''Tetrapod Zoology''. 13 September 2008. Accessed 24 July 2009.〕
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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