New reptiles from the Middle Triassic of Germany and the early evolutionary history of lepidosaurs

鳞翅目是脊椎动物的一个主要分支，有超过9，400个物种，形成了一个生态多样性和地理分布广泛的群体。它们的早期演变和多样化仍然知之甚少。分子数据表明，现存的两个分支，有鳞类和大蜥蜴，可能在三叠纪分裂。不幸的是，在三叠纪岩石中，类似鳞龙的化石非常罕见，除了完整的喙头类外，只有少数已知的茎分类群（鳞龙形目）。这是由于体型小，骨骼骨化不良，以及缺乏对小型四足动物有良好保存潜力的化石Lagerstaetten。在德国西南部巴登-符滕贝格的韦尔贝格下科乌珀，科学发掘最近发现了大量小型鳞蜥形类骨骼。这些发现的骨骼学分析是耗时的，除了在显微镜下进行广泛的检查外，还需要CT数据，这是识别元素并充分了解经常脱节和严重破碎的骨骼的3D结构所必需的。拟议项目的目标是描述和记录新发现的分类群，在保存的大小类的基础上研究个体发育，在广泛的双孔类框架内进行系统发育分析，以及研究鳞龙类干系的特征进化。这个项目将大大增加我们对现代生态和分类学多样性的理解，并将在一般规模上揭示更多关于双足爬行动物的进化。

Lepidosaurs are a major vertebrate clade, with more than 9.400 species forming an ecologically diverse and geographically widespread group. Their early evolution and diversification are still poorly understood. Molecular data indicate that the two extant branches, squamates and tuataras, probably split during Triassic time. Unfortunately, lepidosaur-like fossils are very rare in Triassic rocks, which yielded only few fragmentarily known stem taxa (Lepidosauromorpha) apart from the fully established rhynchocephalians. This results from the small body size and poorly ossified skeletons as well as the poverty of fossil Lagerstaetten with good preservation potential for small tetrapods. In the Lower Keuper of Vellberg (Baden-Württemberg, SW Germany), scientific excavations have recently produced a vast number of small lepidosauromorph skeletons. The osteological analysis of these finds is time-consuming, requiring CT data in addition to extensive examination under the microscope, necessary to identify elements and fully understand the 3d structure of the often disarticulated and heavily crushed skeletons. The objectives of the proposed project are the description and documentation of the newly discovered taxa, the study of the ontogeny on the basis of preserved size classes, the phylogenetic analysis in a wide frame of diapsids, and the study of character evolution in the stem line of lepidosaurs. This project will greatly increase our understanding of how the modern ecological and taxonomic diversity of lepidosaurs first arose, and will shed more light on the evolution of diapsid reptiles on a general scale.