Department of Biological Sciences, The George Washington University, Washington, DC 20052, USA.
Science. 2010 Jan 29;327(5965):571-4. doi: 10.1126/science.1182143.
The fossil record of Jurassic theropod dinosaurs closely related to birds remains poor. A new theropod from the earliest Late Jurassic of western China represents the earliest diverging member of the enigmatic theropod group Alvarezsauroidea and confirms that this group is a basal member of Maniraptora, the clade containing birds and their closest theropod relatives. It extends the fossil record of Alvarezsauroidea by 63 million years and provides evidence for maniraptorans earlier in the fossil record than Archaeopteryx. The new taxon confirms extreme morphological convergence between birds and derived alvarezsauroids and illuminates incipient stages of the highly modified alvarezsaurid forelimb.
与鸟类关系密切的侏罗纪兽脚亚目恐龙的化石记录仍然很少。来自中国西部最晚侏罗世的一种新型兽脚亚目恐龙代表了神秘的兽脚亚目阿尔瓦雷斯龙超科最早的分化成员，并证实该类群是手盗龙类的基础成员，手盗龙类包含鸟类及其最接近的兽脚亚目亲戚。它将阿尔瓦雷斯龙超科的化石记录延长了 6300 万年，并为比始祖鸟更早的手盗龙类提供了证据。新分类单元证实了鸟类和衍生的阿尔瓦雷斯龙之间的极端形态趋同，并阐明了高度特化的阿尔瓦雷斯龙前肢的初始阶段。
