Key Laboratory of Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology & Paleoanthropology, Chinese Academy of Sciences, 142 Xiwai Street, Beijing 100044, China.
Nature. 2010 Apr 29;464(7293):1338-41. doi: 10.1038/nature08965.
Recent discoveries of feathered dinosaur specimens have greatly improved our understanding of the origin and early evolution of feathers, but little information is available on the ontogenetic development of early feathers. Here we describe an early-juvenile specimen and a late-juvenile specimen, both referable to the oviraptorosaur Similicaudipteryx, recovered from the Lower Cretaceous Yixian Formation of western Liaoning, China. The two specimens have strikingly different remiges and rectrices, suggesting that a radical morphological change occurred during feather development, as is the case for modern feathers. However, both the remiges and the rectrices are proximally ribbon-like in the younger specimen but fully pennaceous in the older specimen, a pattern not known in any modern bird. In combination with the wide distribution of proximally ribbon-like pennaceous feathers and elongate broad filamentous feathers among extinct theropods, this find suggests that early feathers were developmentally more diverse than modern ones and that some developmental features, and the resultant morphotypes, have been lost in feather evolution.
最近发现的有羽毛恐龙标本极大地提高了我们对羽毛起源和早期进化的理解，但关于早期羽毛的个体发育信息却很少。在这里，我们描述了两个来自中国辽宁西部早白垩世义县组的幼年标本，均属于似鸟龙类的小盗龙。这两个标本的尾羽和尾羽有显著的不同，这表明在羽毛发育过程中发生了剧烈的形态变化，就像现代羽毛一样。然而，在较年轻的标本中，尾羽和尾羽都是近端带状的，但在较年长的标本中则完全是羽片状的，这种模式在任何现代鸟类中都没有出现过。结合近端带状羽片状羽毛和伸长的宽丝状羽毛在已灭绝的兽脚亚目恐龙中的广泛分布，这一发现表明，早期羽毛在发育上比现代羽毛更加多样化，并且一些发育特征和由此产生的形态类型在羽毛进化中已经丢失。
