New Sclerocephalus species and temnospondyl braincase evolution

The late Paleozoic temnospondyl Sclerocephalus formed an aquatic top predator in various Central European lakes of the Late Carboniferous and early Permian. Despite hundreds of specimens spanning a wide range of sizes, knowledge of the endocranium (braincase and palatoquadrate) remained very insufficient in Sclerocephalus and other stereospondylomorphs, because even large skulls had unossified endocrania. A new specimen from a stratigraphically ancient deposit is recognized as representing a new taxon, S. concordiae n. sp., and reveals a completely ossified endocranium. The sphenethmoid was completely ossified from the basisphenoid to the anterior ethmoid region, co-ossified with the parasphenoid, and the basipterygoid joint was fully established. The pterygoid bears an a slender, S-shaped epipterygoid, which formed a robust pillar lateral to the braincase. The massive stapes was firmly sutured to the parasphenoid. In the temnospondyl endocranium, character evolution involved various ch...晚古生代（Late Paleozoic）离片椎类（temnospondyl）硬鳞螈属（Sclerocephalus）是晚石炭世（Late Carboniferous）至早二叠世（early Permian）中欧各类湖泊中的水生顶级捕食者。尽管已有数百件涵盖宽泛体型范围的标本，但硬鳞螈属及其他离片椎形类（stereospondylomorphs）的脑颅（endocranium，包含颅腔骨与腭方骨）相关认知仍极为不足，这是因为即便体型较大的头骨，其脑颅也存在未骨化的部分。一件产自地层古老沉积物的新标本被认定为代表一个新分类单元——康迪硬鳞螈（S. concordiae n. sp.），该标本揭示了完全骨化的脑颅结构。蝶筛骨（sphenethmoid）从基蝶骨（basisphenoid）到前筛骨区域完全骨化，并与副蝶骨（parasphenoid）愈合成一体，基翼突关节（basipterygoid joint）已完全形成。翼骨（pterygoid）带有纤细的S形上翼骨（epipterygoid），该结构在脑颅外侧形成了坚固的支柱。大型镫骨（stapes）与副蝶骨牢固缝合连接。在离片椎类的脑颅中，性状演化涉及多种……