Sculptured dermal bones as osteological correlates of integumentary structure and physiology of basal tetrapods

在晚古生代脊椎动物征服陆地期间发生的生理变化人们知之甚少，因为在基础四足动物中软体部分的保存是例外的。由于被膜决定了脊椎动物新陈代谢的主要方面，更好地了解基础四足动物的被被结构将有助于理解从鱼类到四足动物以及从非羊膜动物到羊膜动物的转变。真皮骨是非常适合作为骨科相关的皮肤软组织部分，因为它们在真皮内发育，并被神经血管、神经和锚定纤维所穿透。本项目表明，与水生茎四足动物相比，化生组织和紧密堆积的矿化Sharpey纤维存在于基冠四足动物雕刻的真皮骨骼中。这表明，这些更适应陆地的动物获得了更致密的外皮，与骨骼表面的雕塑很好地结合在一起。雕刻性的脊线保护了许多通向外部骨骼表面的血管。在拟议的扩展中，将澄清现存的带有雕塑的鱼类、两栖动物和鳄鱼的真皮骨和覆盖层之间的关系，这些鱼类和鳄鱼是化石形式的现存系统发育支架。通过这种方式，迄今获得的关于基础四足动物皮肤的暗示得到了检验。将确定雕塑图案、雕塑骨表面的血管化和假定的生活方式之间是否存在关联。

The physiological changes that occurred during the conquest of land by vertebrates in the Late Palaeozoic are poorly understood, since soft part preservation is exceptional in basal tetrapods. Because the integument determines major aspects in a vertebrate’s metabolism, a better knowledge of the integumentary structure in basal tetrapods will help to understand the transition from fish to tetrapod and from non-amniote to amniote. Dermal bones are well suited as osteological correlates for integumentary soft parts since they develop within the dermis and are penetrated by noumerous blood vessels, nerves, and anchoring fibres. The present project has shown that in contrast to the aquatic stem-tetrapods, metaplastic tissue and closely packed, mineralised Sharpey’s fibres are present in sculptured dermal bones of basal crown-group tetrapods. This indicates that these more terrestrially adapted animals attained a denser integument that was well integrated with the sculpture of the bone surface. The sculptural ridges protected the numerous vessels that opened to the outer bone surface. In the proposed extension, the relationships between dermal bone and the overlying integument in extant sculpture-bearing fishes, amphibians, and crocodiles will be clarified that serve as extant phylogenetic bracket of the fossil forms. In this way, the hitherto obtained implications for the skin of basal tetrapods are tested. It will be established whether there is a correlation between sculptural pattern, vascularisation of the sculptured bone surface, and presumed mode of life.