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）的多数物种产自北半球，但近年来南半球产出的新标本数量持续增长。本文记述了一种上龙属新物种，为该属在南半球的第二个已知物种，其标本采集自内乌肯省（Neuquén Province）瓦卡穆埃塔组（Vaca Muerta Formation）的晚提通阶（侏罗纪）地层。
阿尔曼扎上龙（Pliosaurus almanzai n. sp.）具有两处独有衍征：一是隅骨参与下颌联合，二是枕髁要么无脊索凹，要么带有若干不规则排布的凹槽。此外，该新种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；具9枚及以上联合齿槽；联合后齿槽数量为15至17枚；副蝶骨无腹脊。
阿尔曼扎上龙（Pliosaurus almanzai n. sp.）的发现表明，具有9枚及以上联合齿槽的上龙属物种一直延续至晚提通阶，这与此前认为仅存在具6枚联合齿槽物种的学术假设相悖。