Atoposaurids were a clade of semiaquatic crocodyliforms known from the Late Jurassic to the latest Cretaceous. Tentative remains from Europe, Morocco, and Madagascar may extend their range into the Middle Jurassic. Here we report the first unambiguous Middle Jurassic (late Bajocian–Bathonian) atoposaurid: an anterior dentary from the Isle of Skye, Scotland, UK. A comprehensive review of atoposaurid specimens demonstrates that this dentary can be referred to T heriosuchus based on several derived characters, and differs from the five previously recognized species within this genus. Despite several diagnostic features, we conservatively refer it to T heriosuchus sp., pending the discovery of more complete material. As the oldest known definitively diagnostic atoposaurid, this discovery indicates that the oldest members of this group were small‐bodied, had heterodont dentition, and were most likely widespread components of European faunas. Our review of mandibular and dental features in atoposaurids not only allows us to present a revised diagnosis of T heriosuchus, but also reveals a great amount of variability within this genus, and indicates that there are currently five valid species that can be differentiated by unique combinations of dental characteristics. This variability can be included in future broad‐scale cladistics analyses of atoposaurids and closely related crocodyliforms, which promise to help untangle the complicated taxonomy and evolutionary history of Atoposauridae. © 2015 The Authors. Zoological Journal of the Linnean Society published by John Wiley & Sons Ltd on behalf of The Linnean Society of London

中文翻译：

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第一个确定的中侏罗纪棘龙科（Crocodylomorpha，Neosuchia），以及关于 Theriosuchus 属的讨论

棘龙科是侏罗纪晚期至白垩纪晚期已知的半水生鳄鱼科的一个分支。来自欧洲、摩洛哥和马达加斯加的暂定遗迹可能将其范围扩展到中侏罗纪。在这里，我们报告了第一个明确的中侏罗纪（巴约阶晚期 - 巴松阶）棘龙：来自英国苏格兰斯凯岛的前齿类。对齿龙科标本的全面审查表明，根据几个派生的特征，这种齿科动物可以被称为 T heriosuchus，并且与该属内的五个先前公认的物种不同。尽管有几个诊断特征，但我们保守地将其称为 T heriosuchus sp.，等待发现更完整的材料。作为已知最古老的具有明确诊断意义的棘龙科，这一发现表明，这个群体中最古老的成员体型小，有异牙列，很可能是欧洲动物群的广泛组成部分。我们对甲龙科的下颌和牙齿特征的回顾不仅使我们能够提出对特氏鳄的修正诊断，而且揭示了该属内的大量变异，并表明目前有五种有效的物种可以通过独特的组合进行区分牙齿特征。这种变异性可以包含在未来对棘龙科和密切相关的鳄鱼科进行大规模分支学分析中，这有望帮助解开棘龙科复杂的分类学和进化史。© 2015 作者。约翰威利出版的林奈学会动物学杂志 &