Since 2002, two fossils of the bird hind-limb are collected in Changma village from the same geologic layers of Gansus yumenensis who is the first mesozoic bird found in China. Compared these to the hind-limb of Gansus yumenensis and extant birds, some differences are found in the morphological characteristics and developmental degree of their skeletons. And one of the fossils shows the features of petal-web. Results show that birds among Genus Gansu are already present to two or more kinds of the adaptive form in the early cretaceous, and they are the oldest birds of being specifically well-adapted to the aquatic environment in the world.%玉门甘肃鸟(Gansus yumenensis)是在中国发现的第一只中生代鸟类化石.2002以来,在玉门市昌马乡同一层位又得到两块鸟后肢标本.通过与玉门甘肃鸟和现生鸟类后肢比较后发现,它们骨骼的部分特征与玉门甘肃鸟化石有所区别,骨骼形态特征、发育的程度不尽相同,其中一块标本显示了瓣蹼的印痕.研究表明,甘肃鸟属在早白垩世就已经存在两种或两种以上的适应类型,也说明甘肃鸟属的鸟类代表了世界上最古老的具有确切证据的适应水生生活的鸟类.
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