Cawley John, Lehmann Jens, Wiese Frank, Kriwet Jürgen
University of Vienna, Geozentrum, Department of Palaeontology, Althanstr. 14, 1090 Vienna, Austria.
University of Bremen, Faculty of Geosciences, Geosciences Collection, Klagenfurter Str. 4, 28359 Bremen, Germany.
Cretac Res. 2020 Aug 4;116:104590. doi: 10.1016/j.cretres.2020.104590. eCollection 2020 Dec.
A new pycnodont taxon, gen. et sp. nov., from the Turonian of the Lower Saxony Basin of Germany is described and its systematic positions is established based on phylogenetic analyses of three specimens using slightly altered data matrices. All analyses display some differences to previous analyses but show very similar results to each other apart from the interpretation of the position of several taxa such as, e.g., . The new pycnodontiform specimens from northwestern Germany are unambiguously identified as a derived member of Pycnodontidae with close relationships to and ? because of the unique combination of characters. One of the three specimens represents a juvenile form. Its morphological characters are limited, but it shares some characters with gen. et sp. nov. and is consequently allocated to the new taxon. The systematic placement of the new taxon, gen. nov., within Pycnodontidae is surprising since it does not display the one autapomorphic character (postparietal brush-like extension for muscle attachment) previously proposed to define this clade, but rather displays a combination of derived and homoplastic characters indicating that the definition of supra-generic taxa needs to be re-evaluated in the future by including more and new taxa. The distribution of pycnodontiform fishes in the Cretaceous appears to concur with changes in global climatic conditions, where high upper-ocean temperatures and high sea levels allow these fishes to migrate into higher latitudes as evidenced by the occurrence of the new taxon and in the Campanian of Sweden.
描述了一个来自德国下萨克森盆地土伦阶的新的厚齿鱼目分类单元，属及种均为新属新种，并基于对三个标本的系统发育分析，使用略有改动的数据矩阵确定了其系统位置。所有分析与之前的分析均存在一些差异，但除了对几个分类单元位置的解释（例如……）之外，彼此之间显示出非常相似的结果。来自德国西北部的新厚齿鱼目标本因独特的特征组合而被明确鉴定为厚齿鱼科的一个衍生成员，与……和……关系密切。三个标本之一代表幼体形态。其形态特征有限，但与新属新种有一些共同特征，因此被归入新分类单元。新分类单元在厚齿鱼科中的系统位置令人惊讶，因为它并未显示出先前提出的用于定义该分支的一个自近裔性状（用于肌肉附着的顶骨后刷状延伸），而是显示出衍生性状和同塑性状的组合，这表明未来需要通过纳入更多新分类单元来重新评估超属分类单元的定义。厚齿鱼目鱼类在白垩纪的分布似乎与全球气候条件的变化一致，即上层海洋高温和高海平面使这些鱼类能够迁移到更高纬度地区，瑞典坎帕阶出现的新分类单元和……就是证据。
