<i>Purranisaurus potens</i> Rusconi, an enigmatic metriorhynchid from the Late Jurassic–Early Cretaceous of the Neuquén Basin

ABSTRACTThe Tithonian record from northwestern Patagonia (Neuquén Basin) documents a complete succession of lower, middle, and late Tithonian marine reptiles. From the late Tithonian–early Berriasian of Patagonia, three marine crocodyliforms have been recorded: <i>Dakosaurus andiniensis</i>, <i>Cricosaurus araucanensis</i>, and <i>Purranisaurus potens</i>. Although <i>P. potens</i> includes the first metriorhynchid skull described from Patagonia, no detailed description and/or illustrations have been published. Since the mid-20th century, several authors have discussed the validity of <i>P. potens</i>. Recent preparation of the type material allowed a detailed description as well as exploration of its phylogenetic relationships. We consider <i>P. potens</i> as a valid taxon characterized by a unique combination of characters, such as medial and posterolateral processes of the frontal forming an angle of 60°; supratemporal fossae reaching the minimum interorbital distance, with the dorsal margin of the supratemporal arch being slightly concave in lateral view; thin bony lamina projecting from the lateral and medial alveolar margins of the maxilla; occipital surface ventral to occipital condyle parallel to transverse plane of skull; well-developed crest that extends along the entire height of the supraoccipital; and orbital process of the quadrate very conspicuous and acute, horizontal, and without bony attachment. Phylogenetic analysis recovers <i>P. potens</i> as deeply nested within Geosaurini and, contrary to previous proposals, not closely related to ‘<i>Metriorhynchus</i>’ <i>casamiquelai</i> and ‘<i>M.</i>’ <i>westermanni</i>. Internal relationships within Geosaurini are unresolved. <i>Purranisaurus</i>, as a monotypic genus, is restricted to the late Tithonian–early Berriasian.http://zoobank.org/urn:lsid:zoobank.org:pub:CDB288F2-087C-4E19-A897-8AB94BD60EC2SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP【摘要】巴塔哥尼亚西北部（内乌肯盆地（Neuquén Basin））的提通阶（Tithonian）沉积记录完整保存了早、中、晚提通阶的海洋爬行动物（marine reptiles）序列。在巴塔哥尼亚提通阶晚期至贝里阿斯阶（Berriasian）早期地层中，已记述三种海洋鳄形类（marine crocodyliforms）：安第斯达克龙（*Dakosaurus andiniensis*）、阿劳坎环鳄（*Cricosaurus araucanensis*）以及强壮浦拉尼鳄（*Purranisaurus potens*）。尽管强壮浦拉尼鳄拥有巴塔哥尼亚地区首个被报道的地蜥鳄科（Metriorhynchidae）头骨，但迄今尚无详细描述及相关插图发表。自20世纪中期以来，已有多位学者对强壮浦拉尼鳄的分类有效性展开讨论。本次研究通过对其正模标本（type material）的最新修复整理，完成了该物种的详细描述，并对其系统发育关系（phylogenetic relationships）进行了探究。我们认为强壮浦拉尼鳄是一个有效分类单元，其具有一系列独特的特征组合：额骨（frontal）的内侧突与后外侧突夹角为60°；颞上窝（supratemporal fossa）延伸至最小眶间距（interorbital distance），颞上弓（supratemporal arch）的背缘在侧视图（lateral view）下呈轻微凹陷；上颌骨（maxilla）的外侧与内侧齿槽缘伸出薄骨板（bony lamina）；枕髁（occipital condyle）腹侧的枕面（occipital surface）与头骨横平面（transverse plane）平行；发育良好的嵴沿上枕骨（supraoccipital）的全高延伸；方骨（quadrate）的眶突极为醒目且尖锐，呈水平状，无骨性附着结构。系统发育分析显示，强壮浦拉尼鳄嵌套于地蜥鳄族（Geosaurini）的较深分支中，且与此前观点相悖的是，其与“‘卡萨米凯勒地蜥鳄（*Metriorhynchus* casamiquelai）’”以及“‘韦斯特曼地蜥鳄（*M.* westermanni）’”的亲缘关系并不密切。地蜥鳄族内部的系统发育关系尚未明确。浦拉尼鳄属（Purranisaurus）为单型属（monotypic genus），其生存时代限定于提通阶晚期至贝里阿斯阶早期。 http://zoobank.org/urn:lsid:zoobank.org:pub:CDB288F2-087C-4E19-A897-8AB94BD60EC2 补充数据：本文的补充材料可通过www.tandfonline.com/UJVP免费获取。