1) Archosaur 2) Archosaurian 3) Archosaurian reptile 
(from the article `sauropterygian`) any of the aquatic reptiles found as fossils from the Mesozoic Era (248 million to 65 million years ago). Sauropterygians include the nothosaurs, the ...
[n] - extinct marine reptile with longer more slender limbs than plesiosaurs and less completely modified for swimming
noun extinct marine reptile with longer more slender limbs than plesiosaurs and less completely modified for swimming