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契氏鸟(Chiappeavis)是首次发现保存有扇状尾羽的反鸟类,显示出尾羽球茎这一结构在较原始的反鸟类中已经发育。详细描述了巨前颌契氏鸟(C.magnapremaxillo)正型标本的骨骼形态学特征。契氏鸟的腭区形态与始祖鸟(Archaeopteryx)相似,而区别于晚白垩世的反鸟类戈壁鸟(Gobipteryx)。即使具有尾羽球茎,鹏鸟类的尾综骨形态也表明该结构发育较差。估算了在契氏鸟中由扇状尾羽所产生的浮力,并与其他早白垩世鸟类进行对比。结果显示,契氏鸟的扇状尾羽所产生的空气浮力小于同时代生活的今鸟型类,这有可能解释了反鸟类中具有空气动力学功能的尾羽形态普遍缺乏的现象。
Chiappeavis was the first to find anti-birds preserved with fan-shaped tail feathers, showing that the structure of the cauda-bulb corbicula has developed in more primitive anti-birds. A detailed description of skeletal morphological features of C. magnaprecogniatus positive specimens. The palatopraxia of Chechnya is similar to Archeopteryx and differs from Gobipteryx in late Cretaceous. Even with the caudal bulb coronet, the penguin caudal bone morphology also suggests that the structure is poorly developed. The buoyancy caused by fan-shaped tail feathers in Cheetahs was estimated and compared with other Early Cretaceous birds. The results show that the air buoyancy produced by Cheetah’s fan-shaped tail feathers is less than that of present-day birds, which may explain the generally lack of aerodynamic-functional tail feathers in anti-birds.