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A therizinosauroid dinosaur with integumentary structures from China


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 Ornithischia1, Sauropodomorpha2,3, Theropoda4,5,6,7,8,9,10,11 and Saurischia sedis mutabilis12. Here we describe a new therizinosauroid from the Yixian Formation (Early Cretaceous, Liaoning, China)13. This new taxon provides fresh evidence that therizinosauroids are nested within the coelurosaurian theropods8,9,10,11. Our analysis suggests that several specialized therizinosauroid characters, such as the Sauropodomorpha-like tetradactyl pes1,2, evolved independently within this group. Most interestingly, this new dinosaur has integumentary filaments as in Sinosauropteryx14,15. 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 birds14,15.

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Figure 1: Beipiaosaurus inexpectus (V11559, holotype).
Figure 2: Beipiaosaurus inexpectus.
Figure 3: Beipiaosaurus inexpectus.
Figure 4: Phylogenetic relationships of Beipiaosaurus inexpectus.


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We thank J. Clark for advice and reviewing the manuscript; Z.-X. Luo for improving the organization and language of the manuscript as well as the use of PAUP 3.11; Z.-H. Zhou and O.Rauhut for discussions; P. Currie, M. Norell, P. Sereno, X.-C. Wu and H. Osmolska for reviews and comments; and the Liaoxi expedition members of the IVPP. Photographs were taken by J. Zhang, electronic photography by L. Oyang, and line drawings are by R.-S. Li, Y.-T. Li, H.-J. Wang and J.-Z. Ding prepared the specimen. This study was supported by research grants from the Chinese Academy of Sciences and the National Natural Science Foundation of China.

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Xu, X., Tang, Zl. & Wang, Xl. A therizinosauroid dinosaur with integumentary structures from China. Nature 399, 350–354 (1999).

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