Therizinosauroidea ('segnosaurs') are little-known group of Asian dinosaurs with an unusual combination of features that, until recently, obscured their evolutionary relationships. Suggested affinities include Ornithischia, Sauropodomorpha, Theropoda and Saurischia sedis mutabilis. Here we describe a new therizinosauroid from the Yixian Formation (Early Cretaceous, Liaoning, China). This new taxon provides fresh evidence that therizinosauroids are nested within the coelurosaurian theropods. Our analysis suggests that several specialized therizinosauroid characters, such as the Sauropodomorpha-like tetradactyl pes, evolved independently within this group. Most interestingly, this new dinosaur has integumentary filaments as in Sinosauropteryx. This indicates that such feather-like structures may have a broad distribution among non-avian theropods, and supports the hypothesis that the filamentous integumentary structures may be homologous to the feathers of birds.
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机译：Therizinosauroidea（'segnosaurs'）是鲜为人知的亚洲恐龙群，具有不寻常的特征组合，直到最近才掩盖了它们的进化关系。建议的亲和性包括鸟眼，Sauropodomorpha，Theropoda和Saurischia sedis mutabilis。在这里，我们描述了来自义县组（中国白垩纪早期）的一种新的鼻龙类。这个新的分类单元提供了新的证据，即脊龙类人猿被嵌套在腔骨龙类兽脚类动物体内。我们的分析表明，在这组动物中，几个专门的鼻龙类动物特征，如类鳞茎类四齿类人猿，是独立进化的。最有趣的是，这种新的恐龙像中龙科动物一样，具有外皮的细丝。这表明这种羽毛状结构在非禽兽脚类动物中可能具有广泛的分布，并支持了丝状外皮结构可能与鸟类的羽毛同源的假说。
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