Pterosaurs from the latest Early and early Middle Jurassic of Argentina and the origin of the Pterodactyloidea

翼龙类的主龙是第一组脊椎动物，实现主动扑翼飞行。在这个组中，衍生的翼龙类至少从晚侏罗世开始代表了最大的分类和生态多样性。翼手龙类化石记录出现于晚侏罗世早期，但晚侏罗世的系统发育关系和多样性表明，它们的起源将被发现于早侏罗世中期甚至晚期。然而，翼龙的化石记录强烈偏向于特殊的Lagerstätten，至少在侏罗纪，北方半球。阿根廷丘布特省早、中侏罗世晚期翼龙化石的发现，对进一步了解翼龙类的侏罗纪演化和翼龙类的起源具有重要意义。由于在丘布特的Toarcian-Bajocian Cañadón Asfalto地层中描述的唯一分类单元代表了单孔层（翼翼龙类所属的分支）的近亲，并且进一步的遗骸显示该分支的特征已经从该地层中已知，因此该单位似乎可以提供关于翼翼龙类起源的新数据。因此，本项目的目标是研究阿根廷丘布特省Cañadon Asfalto组及其等同物的翼龙动物群。我们将建立该动物群的分类多样性，并分析所确定的分类群的系统发育关系。此外，我们计划调查的意义，典型的pterydacalidid bauplan的生态框架和形态演化。

Pterosaurian archosaurs were the first group of vertebrates to achieve active flapping flight. Within this group, the derived pterodactyloids represent the greatest taxonomic and ecological diversity at least from the Late Jurassic onwards. Pterodactyloids appear in the fossil record in the early Late Jurassic, but their phylogenetic relationships and diversity in the Late Jurassic indicate that their origin will be found in the Middle or even late Early Jurassic. However, the fossil record of pterosaurs is strongly biased in favour of exceptional Lagerstätten and, at least in the Jurassic, the northern Hemisphere. Finds of pterosaurs from the latest Early and Middle Jurassic of the province of Chubut, Argentina, thus have a great potential to improve our understanding of the Jurassic evolution of pterosaurs and the origin of pterodactyloids. Since the only taxon described from the Toarcian-Bajocian Cañadón Asfalto Formation in Chubut represents a close relative of monofenestratans (the clade to which pterydactyloids belong), and further remains that show features of this clade are already known from that formation, it seems likely that this unit can provide new data on the origin of pterydactyloids. The objective of the present project is thus a study of the pterosaur fauna from the Cañadon Asfalto Formation and its equivalents in the Argentinean province of Chubut. We will establish the taxonomic diversity of this fauna and analyse the phylogenetic relationships of the identified taxa. Furthermore, we plan to investigate the implications for the eological framework and the morphological evolution of the typical pterydactyloid bauplan.