The fossil record of basal paravians in Gondwana is still poorly known, being limited to the Cretaceous unenlagiids from South America and the problematic Rahonavis from Madagascar. Here we report on a new paravian from the Cenomanian-Turonian (Late Cretaceous) of Río Negro province, NW Patagonia, Argentina. The new taxon exhibits a derived bird-like morphology of the forelimbs (e.g., robust ulna with prominent, anteriorly oriented, and proximally saddle-shaped radial cotyle and wide medial flange on metacarpal I) and a plesiomorphic foot with a raptorial pedal digit II. Phylogenetic analysis recovers the new taxon in a monophyletic clade with Rahonavis, being the sister group of the remaining Avialae and more derived than other non-avian dinosaurs. Both exhibit derived forelimb traits in opposition with their plesiomorphic hind limbs. The position of the new taxon and Rahonavis as stem avialans indicates that Gondwanan basal paravians are represented by two different clades, at least. The new taxon probably constitutes a previously unknown grade in the avian-line theropods in which some flight-related adaptations of the forelimbs are present in cursorial taxa. The present discovery sheds light on the acquisition of flight-related traits in non-avian dinosaurs and on the still poorly known paravian radiation in Gondwana.

中文翻译：

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来自巴塔哥尼亚上白垩纪的新兽脚亚目恐龙为冈瓦纳的帕拉维辐射提供了照明。

冈瓦纳基础paravians的化石记录依然知之甚少，仅限于来自南美和有问题的白垩纪unenlagiids胁空鸟龙属马达加斯加。在这里，我们报道了来自阿根廷西北西北部里奥内格罗省的西诺曼尼亚-突厥人（晚白垩世）的一种新的巴拉圭人。新的分类单元显示出前肢的鸟状形态（例如，健壮的尺骨，在掌骨I上具有突出的，面向前的，近端呈马鞍形的径向子叶和宽的内侧突缘）和具有悬垂脚趾数字II的多形足。系统发育分析可通过Rahonavis在单系进化枝中恢复新的分类单元，是剩下的Avialae的姐妹群体，比其他非禽类恐龙更易衍生。两者均表现出衍生的前肢特征，与它们的后肢形相反。新的分类单元和Rahonavis作为茎类动物的位置表明，冈瓦纳基底的巴拉圭人至少由两个不同的进化枝代表。新的分类单元可能构成了禽系兽脚类动物的一个以前未知的等级，其中前肢的一些与飞行相关的适应性出现在光标分类单元中。本发现揭示了在非禽类恐龙中与飞行有关的性状的获取以及在冈瓦纳仍鲜为人知的巴拉圭辐射。