The cranium of Proviverra typica (Mammalia, Hyaenodonta) and its impact on hyaenodont phylogeny and endocranial evolution

We describe the first endocast reconstruction of a hyaenodont mammal based on X‐ray microtomography. The endocast belongs to the type material of the European hyaenodont Proviverra typica. We performed phylogenetic analysis to contextualize the evolution of endocranial size and complexity in Hyaenodonta. We added several European hyaenodonts and modified several codings of the most recent character–taxon matrix established to question the relationships within Hyaenodonta. Including these new species in a phylogenetic analysis reveals a new clade: Hyaenodontoidea. Comparisons with several previously described endocasts show that there was an increase in complexity in the convolutions of the encephalon within Hyaenodontidae history. Moreover, the analysis of the encephalization quotient reveals that the endocranium of the Hyaenodonta is not smaller than those of fossil Carnivora or some extant Carnivora. Therefore, the extinction of Hyaenodonta may not be linked to the relative size of hy...我们首次基于X射线显微断层扫描（X-ray microtomography）技术，完成了一件鬣齿兽类哺乳动物的颅内模重建。该颅内模属于欧洲鬣齿兽类典型前兽（Proviverra typica）的模式标本。我们开展了系统发育分析，以厘清鬣齿兽类的颅腔尺寸与复杂程度的演化脉络。本次研究新增了多种欧洲鬣齿兽类类群，并对先前为探讨鬣齿兽类内部系统发育关系所建立的最新性状-分类单元矩阵的多项编码进行了修正。将这些新类群纳入系统发育分析后，我们发现了一个新的演化支：鬣齿兽总科（Hyaenodontoidea）。通过与多份已发表的颅内模标本进行比对，结果显示在鬣齿兽科的演化历史中，其大脑皮层沟回的复杂程度呈上升趋势。此外，对脑化商数（encephalization quotient）的分析表明，鬣齿兽类的颅腔尺寸并不小于化石食肉目（Carnivora）类群，亦不小于部分现生食肉目（Carnivora）类群。因此，鬣齿兽类的灭绝或许与其相对脑容量并无关联……