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过程中发生的生理变化，人们知之甚少，因为在基生四足动物中，柔软的部分保存得非常好。由于被膜决定了脊椎动物新陈代谢的主要方面，因此更好地了解基础四足动物的被膜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。真皮骨在真皮内发育，并被大量血管、神经和锚定纤维穿透，因此非常适合作为真皮软组织的骨学相关物。目前的研究表明，与水生茎型四足动物不同，基冠类四足动物的真皮骨骼中存在化生组织和紧密堆积的矿化Sharpey’s纤维。这表明这些更适应陆地的动物获得了更密集的被皮，与骨骼表面的雕刻很好地结合在一起。雕塑般的脊状结构保护着通往外骨表面的众多血管。在拟议的扩展，真皮骨之间的关系，并在现有的雕刻承载鱼类，两栖动物和鳄鱼的上覆被澄清，作为现存的系统发育支架的化石形式。通过这种方式，迄今为止获得的对基底四足动物皮肤的影响得到了检验。它将确定雕塑模式，雕塑骨表面的血管化和假定的生活模式之间是否存在相关性。

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.