玉门甘肃鸟(Gansusyumenensis)是中国发现的第一只中生代鸟类化石。该化石产自甘肃西北部下沟组,时代与辽宁西部产热河生物群的早白垩世地层的时代大体相当。该鸟类趾节拉长,很短的爪具有较尖锐的屈肌结节,因而被认为是一种适应于水生生活的鸟类。玉门甘肃鸟的建立最初仅依据一件左足标本,直到最近又发现了少量可供进一步研究的新标本。本文描述了一件新的玉门甘肃鸟的完整后肢化石,标本在远端趾节之间显示出清晰的蹼的构造。这为玉门甘肃鸟具有发育足蹼的观点提供了最直接的证据。玉门甘肃鸟也成为世界上已知最古老的适应于水生生活环境的鸟类。 Gansusyumenensis is the first Mesozoic bird fossil found in China. The fossil was produced from the Xiagou Formation in the northwestern part of Gansu Province. The era was roughly equivalent to that of the Early Cretaceous strata of the Jehol Reh Biota in western Liaoning. The bird’s toes elongated, short claws with sharp flexor nodules, and therefore is considered to be a suitable aquatic life of birds. The establishment of the Yumen Gansu bird was initially based on only one left-footed specimen, and until recently few new specimens were found for further study. This article describes a new intact hind limb fossil of the Yumen Gansu bird that shows a clear webbed configuration between the distal toe nodes. This provides the most direct evidence that Yumen Gansu bird has developed foot webs. Yumen Gansu Bird has also become the world’s oldest known to adapt to the aquatic environment of birds.