辽西早白垩世一反鸟类新发现

Discovery of a new enantiornithine bird from Lower Cretaceous of western Liaoning,China

描述发现于中国辽宁朝阳早白垩世九佛堂组地层中的一件鸟类标本。该标本体型较小,具有许多反鸟类的近裔特征。通过对新标本后肢形态特征的分析,可判断其为一小型树栖反鸟类。新标本具有发育的前肢和进步的乌喙骨,及发育滞后的后肢和相对原始的胸骨形态。胸骨长宽比约为1,顶端呈圆弧形,两个后侧突末端不膨大,中央突末端稍扩大,龙骨突基本不发育等。新标本同时具有反鸟类的原始和进步特征,以及原始的胸骨特征。其综合特征不同于已知任意一种小型反鸟类,因此建立一个反鸟类新属种——普通小反鸟(Microenantiornis vulgaris gen.et sp.nov.)。

A new enantiornithine bird from Early Cretaceous Jiufotang Formation in Chaoyang of western Liaoning is described. This new small-sized bird shows several enantiornithine synapomorphies. Based on the morphological features of the hindlimb,this new specimen represents an arboreal enantiornithine bird. It has developmental forelimb and progressive coracoid,as well as lagging hindlimb and relatively primitive sternum morphology. The ratio of the length to the width of the sternum is approximately 1. Rostral margin of the sternum is rounded,the distal end of the outermost trabecula of the sternum is not expanded,and the distal end of the caudal trabecula is slightly expanded,with the keel of sternum absent. Its skeleton displays a mosaic of both primitive and derived characters,as well as the primitive sternum features. Its synthetic characters is distinguishable from other known small-sized enantiornithines,therefore this specimen represents a new genus and species： Microenantiornis vulgaris gen. et sp. nov.