孔子鸟化石研究新进展

NEW ADVANCES IN THE STUDY OF THE PRIMITIVE BIRD CONFUCIUSORNIS

孔子鸟 ( Confuciusornis)是最早具有角质喙及尾综骨的原始鸟类化石 ,同时兼具明显原始和显著进步的特征 ,在研究鸟类的早期演化方面具有极为重要的意义。孔子鸟头骨为典型的原始双孔类型 ,其角质喙与其它鸟类的角质喙是在进化过程中分别独立获得的。孔子鸟具有肋骨钩状突 ,这很可能代表着一种原始性状。孔子鸟飞羽发达 ,但未发育小翼羽。孔子鸟与长城鸟( Changchengornis)构成一组姊妹群 ,反鸟类 ( Enantiornithes)与今鸟类 ( Ornithurae)亦构成一组姊妹群 ,这两类群又互为姊妹群关系。在孔子鸟已命名的 4个种中 ,川州种 ( C.chuanzhous)和孙氏种 ( C.sunae)是圣贤种 ( C.sanctus)的晚出同物异名 ,应予以废弃。孔子鸟主要适应陆地生活 ,具有较强的飞行能力 ,并能够从地面起飞。目前关于孔子鸟的地质时代仍存在着晚侏罗世与早白垩世之争 ,但大多数动物化石都证实了孔子鸟层为晚侏罗世的观点。

Confuciusornis, the earliest avian taxon with beak and pygostyle, is extremely important in the study of the early evolution of birds. Its skull is of typical diapsid plan. The beak is quite robust-its teeth were lost independently of other birds. The presence of the long uncinate processes in Confuciusornis is thought to be primitive for birds. The flight feathers are well developed, but the alula is not present. Confuciusornis is the sister-taxon of Changchengornis, and both are placed within the same family of Confuciusornithidae, which is considered to be the sister-group of the Ornithothoraces composed of the Enantiornithes and the Ornithurae. Within the four species of Confuciusornis, C. chuanzhous and C. sunae are considered to be junior synonyms of C. sanctus. It is argued that the Confuciusornis were ill suited for tree climbing, but were able to fly and take off from the ground. Most fossil animals produce the evidence that the Confuciusornis-bearing beds should be the Late Jurassic in age alth ough the Early Cretaceous is accepted by some researchers.