英国和爱尔兰研究人员对鸟类羽毛化石进行的新研究显示，始祖鸟和孔子鸟等早期鸟类只能算是蹩脚“飞行员”。由于羽毛结构不够强壮，它们无法振翅高飞，最多只能滑翔。
现代鸟类的动力飞行依赖于它们身上长着强壮且轻便的中空羽轴，在振翅时既强有力，又可减少重量。而英国曼彻斯特大学和爱尔兰都柏林大学学院研究人员对始祖鸟和孔子鸟化石进行研究后发现，二者的羽轴比现代鸟类要细得多。但遗憾的是，从化石中不能看出早期鸟类的羽轴是中空还是实心。
这是科学家根据研究推断的中华龙鸟色彩复原图。
研究人员分析鸟类飞行时作用于羽毛的各种力量后认为，如果始祖鸟和孔子鸟的羽轴是中空的，那么它们振翅时，细薄的羽轴会像吸管一样发生变形；即使羽轴是实心的，它们最多也只能勉强滑翔。因此，早期鸟类不具备动力飞行的本领。
始祖鸟生活在距今1.4亿年的侏罗纪晚期，孔子鸟则生活在距今1亿年的白垩纪早期。目前，生物学界关于鸟类的进化尚存诸多疑问。一种被普遍接受的理论认为，最早的鸟类是由长有羽毛的小型恐龙进化而来。
这项研究成果发表在最新出版的《科学》杂志上。
Science 14 May 2010:
Vol. 328. no. 5980, pp. 887 - 889
DOI: 10.1126/science.1188895
Reports
Narrow Primary Feather Rachises in Confuciusornis and Archaeopteryx Suggest Poor Flight Ability
Robert L. Nudds1,* and Gareth J. Dyke2
The fossil birds Archaeopteryx and Confuciusornis had feathered wings resembling those of living birds, but their flight capabilities remain uncertain. Analysis of the rachises of their primary feathers shows that the rachises were much thinner and weaker than those of modern birds, and thus the birds were not capable of flight. Only if the primary feather rachises were solid in cross-section (the strongest structural configuration), and not hollow as in living birds, would flight have been possible. Hence, if Archaeopteryx and Confuciusornis were flapping flyers, they must have had a feather structure that was fundamentally different from that of living birds. Alternatively, if they were only gliders, then the flapping wing stroke must have appeared after the divergence of Confuciusornis, likely within the enantiornithine or ornithurine radiations.
