The braincase anatomy of the Pennsylvanian diadectomorph Limnoscelis dynatis is described in detail, based upon high-resolution X-ray microcomputed tomography. Both supraoccipitals and most of the prootics and opisthotics are preserved. The known portions of the left prootic, opisthotic, and supraoccipital enclose complete sections of the endosseous labyrinth, including the anterior, posterior, and lateral semicircular canals, the vestibule, the cochlear recess, and the canal for the endolymphatic duct. The fossa subarcuata is visible anteromedial to the anterior semicircular canal. The presumed endolymphatic fossae occur in the dorsal wall of the posteromedial portion of the supraoccipital. Both the fossa subarcuata and the fossa endolymphatica lie in the cerebellar portion of the cranial cavity. In order to investigate the phylogenetic position of L. dynatis we used a recently published data matrix, including characters of the braincase, and subjected it to maximum parsimony analyses under a variety of character weighting schemes and to a Bayesian analysis. Limnoscelis dynatis emerges as sister taxon to L. paludis, and both species form the sister group to remaining diadectomorphs. Synapsids and diadectomorphs are resolved as sister clades in ~90% of all the most parsimonious trees from the unweighted analysis, in the single trees from both the reweighted and the implied weights analyses, as well in the Bayesian tree.

中文翻译：

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高分辨率 X 射线显微计算机断层扫描显示晚石炭纪四足动物 Limnoscelis dynatis (Diadectomorpha) 的脑壳和内耳解剖结构

基于高分辨率 X 射线显微计算机断层扫描详细描述了宾夕法尼亚 diadectomorph Limnoscelis dynatis 的脑壳解剖结构。上枕骨和大部分质体和假体都保留了下来。左前牙、上牙和枕上的已知部分包围了内迷路的完整部分，包括前半规管、后半规管、外半规管、前庭、耳蜗隐窝和内淋巴管。弓下窝在前半规管的前内侧可见。假定的内淋巴窝发生在枕上后内侧部分的背壁。颅底窝和内淋巴窝均位于颅腔的小脑部分。为了研究 L. dynatis 的系统发育位置，我们使用了最近发布的数据矩阵，包括脑壳的特征，并在各种特征加权方案下对其进行最大简约分析和贝叶斯分析。Limnoscelis dynatis 作为 L. paludis 的姊妹分类群出现，并且这两个物种与剩余的双亚型形成姊妹组。在来自未加权分析的所有最简约树的约 90% 中，在来自重新加权和隐含权重分析的单棵树中，以及在贝叶斯树中，Synapsids 和 diadectomorphs 被解析为姐妹进化枝。Limnoscelis dynatis 作为 L. paludis 的姊妹分类群出现，并且这两个物种与剩余的双亚型形成姊妹组。在来自未加权分析的所有最简约树的约 90% 中，在来自重新加权和隐含权重分析的单棵树中，以及在贝叶斯树中，Synapsids 和 diadectomorphs 被解析为姐妹进化枝。Limnoscelis dynatis 作为 L. paludis 的姊妹分类群出现，并且这两个物种与剩余的双亚型形成姊妹组。在来自未加权分析的所有最简约树的约 90% 中，在来自重新加权和隐含权重分析的单棵树中，以及在贝叶斯树中，Synapsids 和 diadectomorphs 被解析为姐妹进化枝。