Data from: Small crocodyliform from the Lower Cretaceous (late Aptian) of central Texas and its systematic relationship to the evolution of Eusuchia

A new Early Cretaceous neosuchian crocodyliform is recognized on the basis of two skulls and postcranial material collected from the late Aptian Twin Mountains Formation at Proctor Lake, central Texas. The new species, Wannchampsus kirpachi, is distinguished by a unique combination of characters including an enlarged third maxillary tooth, internal choanae bordered anteriorly by the palatines and by the pterygoids posteriorly and laterally, anterior margin of the choanae situated at the posterior edge of the suborbital fenestrae, a median crest along the midline of the parietal and frontal, and procoelous vertebrae. A phylogenetic analysis recovered the new taxon as the sister to the ‘Glen Rose form,' an undescribed taxon of neosuchian. Together, with Shamosuchus, Batrachomimus, and Rugosuchus, they form a monophyletic group, Paralligatoridae, that is the sister clade to Eusuchia within Neosuchia. The Proctor Lake taxon and the undescribed yet widely discussed ‘Glen Rose form' are referable to the same genus.

本研究基于采自德克萨斯州中部普罗克特湖晚阿普第阶双山组的两件头骨及颅后骨骼材料，记述并确立了一种早白垩世新鳄类（neosuchian）鳄形超目（crocodyliform）新类群。该新种为沃安坎普鳄（Wannchampsus kirpachi），其凭借一系列独特的性状组合区别于其他类群：上颌第三齿膨大；内鼻孔（internal choanae）的前缘由腭骨（palatines）环绕，后缘及两侧由翼骨（pterygoids）构成；内鼻孔前缘处于眶下孔（suborbital fenestrae）后缘位置；顶骨（parietal）与额骨（frontal）的中线处发育有中脊；椎骨为前凸型（procoelous vertebrae）。系统发育分析结果显示，该新分类单元与"格伦罗斯类群（Glen Rose form）"构成姊妹群，后者为一种未命名的新鳄类类群。该新类群与沙摩鳄（Shamosuchus）、巴特拉科莫鳄（Batrachomimus）以及皱纹鳄（Rugosuchus）共同构成单系群副短吻鳄科（Paralligatoridae），该类群是新鳄亚目（Neosuchia）内真鳄类（Eusuchia）的姊妹演化支。本次研究的普罗克特湖类群与尚未命名但已被广泛讨论的"格伦罗斯类群"可归入同一属。