Data from: A new Pliosaurus species (Sauropterygia, Plesiosauria) from the Upper Jurassic of Patagonia: new insights on the Tithonian morphological disparity of mandibular symphyseal morphology

Abstract.—Most species of the genus Pliosaurus come from the Northern Hemisphere, however a growing number of new specimens are now available from the Southern Hemisphere. Here a new species of Pliosaurus is described, the second for the genus from the Southern Hemisphere, collected from the upper Tithonian (Jurassic) levels of the Vaca Muerta Formation, Neuquén Province. Pliosaurus almanzai n. sp. is characterized by two autapomophies: angular participating in the mandibular symphysis and occipital condyle without a notochordal pit or several, irregularly-arranged grooves. Additionally P. almanzai can be differentiated from other Pliosaurus species by the following characters: trihedral teeth; nine or more symphyseal alveoli; 15-17 post symphyseal alveoli; and parasphenoid without ventral keel. Pliosaurus almanzai n. sp. shows that Pliosaurus species with nine or more 9 symphyseal alveoli persisted until the late Tithonian, contrary to previous assumptions that only species with six symphyseal alveoli were present.摘要：上龙属（Pliosaurus）的绝大多数物种产自北半球，但目前南半球出土的新标本数量正逐步增多。本文记述该属在南半球发现的第二个新物种——阿尔曼萨上龙（Pliosaurus almanzai）新种（n. sp.），其标本采集自阿根廷内乌肯省瓦卡穆埃尔塔组侏罗系提通阶上部地层。该新种具有两处独有衍征：一是隅骨参与下颌联合，二是枕髁既无脊索凹，也不存在若干不规则排列的沟槽。此外，阿尔曼萨上龙可通过以下特征与其他上龙属物种相区分：牙齿呈三面体形；下颌联合处齿槽数量不少于9个；联合后齿槽数量为15至17个；副蝶骨无腹侧龙骨突。阿尔曼萨上龙新种的发现表明，下颌联合处齿槽数量不少于9个的上龙属物种一直存续至提通阶晚期，这与此前仅认为存在下颌联合处齿槽为6个的上龙物种的学术假设相悖。