背景:UnenlagiineParavians是与了解鸟类起源最相关的冈瓦南兽脚类恐龙进化枝之一,然而他们的化石记录仍然不完整,大多数分类单元由零碎的材料代表和/或由漫长的时间间隙隔开,令人沮丧的尝试来表征unenlagiine进化。
结论:在这里,我们描述了滴芩石斑原。等sp.11月。,来自巴塔哥尼亚北部内乌肯省内乌肯盆地上白垩纪(Santonian)BajodelaCarpa组的一个新的unenlagiine分类群,阿根廷填补了这些兽脚类动物化石记录中巨大的地层空白。尽管仅从非常不完整的颅后骨骼中得知,潜琴保存的骨骼与其他unlagiines中的相应元素不同,为建立新的分类单元辩护。此外,在几个形态学方面,Diuqin的肱骨似乎介于Neuquén盆地地质上较旧的unlagiines的肱骨之间(例如,Unenlagiaspp.来自Turonian-ConiacianPortezuelo组)和地层较年轻的地层,来自坎帕尼亚-马斯特里赫蒂艾伦编队的体形较大的澳大利亚探险家卡巴扎。因此,新分类群的形态似乎表明了unenlagiine进化的过渡阶段。系统发育分析将吊琴恢复为具有多个合理系统位置的副鸟,但与Unenlagiinae的亲和力最强。新形式的肱骨在其远端附近表现出亚圆形穿刺,被解释为最有可能由锥形齿状的鳄鱼形留下的进食痕迹,哺乳动物,或者兽脚类,后者可能对应于megaraptorid或另一个unenlagiine个体。因此,除了填补Unenlagiine进化史中重要的形态和时间空白之外,新的分类单元还提供了与这些兽脚类动物的古生态学有关的信息。
BACKGROUND: Unenlagiine paravians are among the most relevant Gondwanan theropod dinosaur clades for understanding the origin of birds, yet their fossil record remains incomplete, with most taxa being represented by fragmentary material and/or separated by lengthy temporal gaps, frustrating attempts to characterize unenlagiine evolution.
CONCLUSIONS: Here we describe Diuqin lechiguanae gen. et sp. nov., a new unenlagiine taxon from the Upper Cretaceous (Santonian) Bajo de la Carpa Formation of the Neuquén Basin of Neuquén Province in northern Patagonia, Argentina that fills a substantial stratigraphic gap in the fossil record of these theropods. Although known only from a very incomplete postcranial skeleton, the preserved bones of Diuqin differ from corresponding elements in other unenlagiines, justifying the erection of the new taxon. Moreover, in several morphological aspects, the humerus of Diuqin appears intermediate between those of geologically older unenlagiines from the Neuquén Basin (e.g., Unenlagia spp. from the Turonian-Coniacian Portezuelo Formation) and that of the stratigraphically younger, larger-bodied Austroraptor cabazai from the Campanian-Maastrichtian Allen Formation. Consequently, the morphology of the new taxon appears to indicate a transitional stage in unenlagiine evolution. Phylogenetic analysis recovers Diuqin as a paravian with multiple plausible systematic positions, but the strongest affinity is with Unenlagiinae. The humerus of the new form exhibits subcircular punctures near its distal end that are interpreted as feeding traces most likely left by a conical-toothed crocodyliform, mammal, or theropod, the latter potentially corresponding to a megaraptorid or another unenlagiine individual. Thus, in addition to filling important morphological and temporal gaps in unenlagiine evolutionary history, the new taxon also offers information relating to the paleoecology of these theropods.