A new Lower Cretaceous bird from China and tooth reduction in early avian evolution
A new Lower Cretaceous bird from China and tooth reduction in early avian evolution
复制标题
DOI：
10.1098/rspb.2009.0885
复制
发表时间：
2010-01
期刊：
影响因子：
--
通讯作者：
Zhonghe Zhou;Fucheng Li
中科院分区：
文献类型：
--
作者：
Zhonghe Zhou;Fucheng Li
中国鸟类一新属新种--杨氏中建鸟新种（Zhongjianornisyangigen. etsp. nov.）在辽宁下白垩统九佛堂组湖相沉积中发现了一种新的沉积相。该新分类群的特点是具有以下特征的组合：上下颌无牙，吻尖，肱骨有大而结实的三角胸嵴，第二节手指比第一节手指长，翼状和大手指的指甲长度相似，但明显短于相应的倒数第二节手指，胫跗骨纤细，长度是跗跖骨的两倍以上，第四跖骨比其他跖骨长系统发育分析表明，中建鸟属在系统发育上与孔子鸟属以及中生代优势类群反鸟目（Enantiornithes）和鸟亚科（Ornithurae）处于同一基础，为研究早白垩世鸟类的多样性提供了重要的新信息。它也代表了最基本的鸟类，完全没有牙齿，这表明牙齿脱落在早期鸟类进化中比预期的更常见，并且鸟类喙独立地出现在几个鸟类谱系中，最有可能是对选择压力的反应。最后，一个显着扩大的肱骨胸三角肌嵴的存在表明，中建鸟与其他基础鸟类，如Jeholornis，Sapeornis和Confuciusornis共享一个独特的模式，以适应飞行与更先进的鸟类，而不是具有细长的胸骨和突出的龙骨。
A new avian genus and species, Zhongjianornis yangi gen. et sp. nov., is reported from the Lower Cretaceous lacustrine deposits of the Jiufotang Formation in Liaoning, northeast China. The new taxon is characterized by possessing the following combination of features: upper and lower jaws toothless, snout pointed, humerus with large and robust deltopectoral crest, second phalanx of the major manual digit longer than the first phalanx, unguals of the alular and major digits of similar length and significantly shorter than the corresponding penultimate phalanges, tibiotarsus slender and more than twice the length of the tarsometatarsus, and metatarsal IV longer than the other metatarsals. Phylogenetic analysis indicates that Zhongjianornis is phylogenetically basal to Confuciusornis and the dominant Mesozoic avian groups, Enantiornithes and Ornithurae, and therefore provides significant new information regarding the diversification of birds in the Early Cretaceous. It also represents the most basal bird that completely lacks teeth, suggesting that tooth loss was more common than expected in early avian evolution and that the avian beak appeared independently in several avian lineages, most probably as a response to selective pressure for weight reduction. Finally, the presence of a significantly enlarged humeral deltopectoral crest suggests that Zhongjianornis shares with other basal birds such as Jeholornis, Sapeornis and Confuciusornis a distinctive mode of adaptation for flight contrasting with that seen in more advanced birds, which instead possess an elongated sternum and a prominent keel.