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Abstract
Data from Xu et al.1 document that the tail feathers of the juvenile Similicaudipteryx specimen are very different in morphology from previously described PRPFs, in which the ribbon-like basal portion is formed completely by the lateral expansion and vertical compression of the rachis (Supplementary Fig. 3 in Xu et al.1). [...] to both the broad proximal rachises of basal birds and Epidexipteryx, and the horny feather sheaths referred to by Prum1, the ribbon-like portions of the PRPFs of the smaller Similicaudipteryx specimen may represent hollow structures similar to the broad monofilaments seen in more basal theropods6.Admittedly, two-dimensional preservation makes it difficult to judge which identification is correct, but further early juvenile Similicaudipteryx specimens with normal flight feathers would support Prum's interpretation. Competing financial interests: declared none. doi:10.1038/nature09481 Xing Xu1, Xiaoting Zheng2&Hailu You3 1Key Laboratory of Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology & Paleoanthropology, Chinese Academy of Sciences, 142 Xiwai Street, Beijing 100044, China. e-mail: [email protected] 2Shandong TianyuMuseumofNature, Pingyi, Shandong 273300, China. 3Institute of Geology, Chinese Academy of Geological Sciences, 26 Baiwanzhuang Road, Beijing 100037, China.