The ontogeny of the dwarf sauropod Europasaurus holgeri and the phylogeny of basal Macronaria (Saurischia, Sauropoda)

蜥脚类动物是有史以来最大的陆地动物，它的进化至今仍只被部分了解。特别是亚组Macronaria的基本形式仅被示例性地研究过，但它们的起源，特征进化，分布和古生物学的细节在很大程度上是未知的。近年来的新发现的财富允许通过两种密切相关的方法对这些问题进行详细调查：（1）作为起点，为了更好地了解蜥脚类恐龙的系统发育意义，将对北方德国上侏罗纪保存得非常完好的大型底栖类欧洲龙（Europasaurus holgeri）的解剖学个体发育变异进行详细研究（尤其是大型动物）解剖学特征。此外，第一次可以描述恐龙与岛屿侏儒症有关的骨骼变化。2)基于对欧罗巴龙解剖学的了解，大量的基底大型动物分类群的解剖学将被（重新）检查并编码在新开发的特征矩阵中，以产生基底大型动物的详细系统发育。更好地了解这个群体内的系统发育关系将澄清欧罗巴龙的位置，并将使这一重要的蜥脚类动物群体的起源和分布的古生物地理模型的发展成为可能。对欧罗巴龙矮化的时间、克里思和生态背景的理解也将高度依赖于这些结果。

The evolution of the sauropods, the group that contains the largest land animals of all times, is still only partly understood. Especially the basal forms of the subgroup Macronaria have been studied only exemplarily, but details of their phylogeny, character evolution, distribution, and palaeobiology are largely unknown. The wealth of new finds in recent years allows for a detailed investigation of these issues by means of two closely related approaches: 1) As a starting point, ontogenetic variations in the anatomy of the exceptionally well preserved basal macronarian Europasaurus holgeri from the Upper Jurassic of northern Germany will be studied in detail to get a better understanding of the phylogenetic significance of sauropod (especially macronarian) anatomical characters. Moreover, for the first time osteological changes related to island dwarfism can be described for dinosaurs. 2) Based on this knowledge about the anatomy of Europasaurus, the anatomy of a high number of basal macronarian taxa will be (re-)examined and coded in a newly developed character matrix, to produce a detailed phylogeny of basal Macronaria. The better understanding of phylogenetic relationships within this group will clarify the position of Europasaurus, and will make possible the development of palaeobiogeographical models of origin and distribution of this important group of sauropods. The understanding of time, tempo and ecological context of dwarfing in Europasaurus will also highly depend on these results.