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，其进化仍然只有一部分人知道。特别是长尾轮虫亚组的基本形态只进行了范例研究，但关于它们的系统发育、特征进化、分布和古生物学的细节在很大程度上是未知的。近年来大量的新发现使得通过两种密切相关的方法来详细研究这些问题成为可能：1)作为起点，将详细研究德国北部上侏罗世保存极为完好的基生大龙类Europasaurus holgeri的个体发育变异，以更好地理解蜥脚类(尤其是大龙类)解剖特征的系统发育意义。此外，与岛屿侏儒症相关的骨学变化首次可以描述为恐龙。2)基于对Europasaurus解剖学的了解，我们将(重新)研究大量的基本大体类群的解剖结构，并将其编码到一个新开发的特征矩阵中，以产生一个详细的基本大体类群的系统发育。更好地了解这一类群内的系统发育关系将澄清欧帕龙的位置，并将使这一重要类群蜥脚类起源和分布的古生物地理模型的发展成为可能。对欧洲龙矮化的时间、节奏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.