Jurassic terrestrial vertebrates from Chubut Province, Argentina: implications for the differentiation of terrestrial vertebrate faunas during the Jurassic

侏罗纪是我们了解脊椎动物进化的一个重要时期，因为许多重要的进化枝都是在这个时期起源和/或经历了一次重要的辐射。然而，我们对陆生脊椎动物侏罗纪进化的理解几乎完全基于北半球的化石记录。到目前为止，冈瓦纳晚侏罗世唯一重要的动物群是坦桑尼亚的腾达古鲁组，但由于缺乏可比较的冈瓦纳动物群，目前不可能对冈瓦纳动物群可能与劳拉动物群不同或相似的原因提出有充分根据的假设。除了可能的变异和由于泛大陆开始分裂而可能增加的地方性外，早侏罗世末期的一次灭绝事件最近成为焦点，这似乎对至少一些陆生脊椎动物的进化支产生了深远的影响。在本项目的第一个资助期，我们在阿根廷Chubut省的上侏罗统Cañadón Calcáreo组勘探脊椎动物化石。可以找到许多新的脊椎动物遗骸，至少部分可以挖掘出来。新发现的化石包括来自这一地层的第一具翼龙遗骸，以及来自南美洲晚侏罗世的第一具阿贝利龙兽脚亚目和剑龙遗骸。一个小型兽脚亚目恐龙Pandoravenator的新标本表明，这个分类群代表了冈瓦纳已知的最古老的心骨龙，而一个新的蜥脚类分类群，目前仍在准备中，有望为腾达古鲁组几个有问题的蜥脚类动物的分类和系统位置提供新的见解。一个新的兽脚亚目由至少三个标本代表，这些标本加在一起几乎显示了这个新分类单元的整个骨学。它显示了与神秘的Chilesaurus的相似之处，因此可能有助于澄清这个问题属的系统位置。最后，发现了更多的标本，但到目前为止还没有挖掘出来，包括至少两个部分铰接的蜥脚类骨骼。在申请的第二个资助期内，我们希望继续这项工作。我们将对新发现进行发掘和准备，并计划完成新的蜥脚类动物和新的兽脚类动物分类群的准备和科学研究。进一步的目标是终止一个正在进行的博士项目，该项目研究Cañadón Calcáreo组的地质和古环境，以及对同一省内一些更古老的侏罗纪单元的潜力进行评估，以提供关于早侏罗世末期灭绝事件的进化影响的证据。

The Jurassic is an important time for our understanding of vertebrate evolution, as many important clades originated and/or experienced an important radiation during this period. However, our understanding of the Jurassic evolution of terrestrial vertebrates is almost entirely based on the fossil record of the Northern Hemisphere. The only important fauna from the Late Jurassic of Gondwana is so far that of the Tendaguru Formation of Tanzania, but in the absence of comparable Gondwanan faunas it is currently impossible to formulate well-founded hypotheses about the reasons for possible differences or similarities with Laurasian faunas. Apart from possible vicariance and possibly increasing endemism due to the beginning breakup of the supercontinent Pangea, an extinction event towards the end of the Early Jurassic has recently come into focus, which seems to have had a profound impact on at least some clades of terrestrial vertebrates. In the first funding period of the present project, we explored the Upper Jurassic Cañadón Calcáreo Formation in Chubut Province, Argentina, for vertebrate fossils. Numerous new vertebrate remains could be located and at least partially be excavated. Among the new finds are the first pterosaur remains from this formation and the first abelisaurid theropod and stegosaur remains from the Late Jurassic of South America. A new specimen of the small theropod dinosaur Pandoravenator shows this taxon to represent the oldest coelurosaur known from Gondwana, and a new sauropod taxon, which is currently still in preparation, promises to give new insights into the taxonomy and systematic position of several problematic sauropods from the Tendaguru Formation. A new theropod is represented by at least three specimens, which together show almost the entire osteology of the new taxon. It shows similarities with the enigmatic Chilesaurus and might thus help to clarify the systematic position of this problematic genus. Finally, more specimens have been found, but not excavated so far, including at least two partially articulated sauropod skeletons. In the second funding period applied for here we want to continue this work. The new finds will be excavated and prepared, and we plan to finish the preparation and scientific study of the new sauropod and the new theropod taxon. A further aim is the termination of an ongoing PhD project on the geology and palaeoenvironments of the Cañadón Calcáreo Formation as well as an evaluation of the potential of some older Jurassic units within the same province to provide evidence on the evolutionary effects of the end-Early Jurassic extinction event.