中国发现从始祖鸟到反鸟的重要缺失环节

最近在中国辽宁省北票地区中生代义县组地层中又发现了迄今最为原始的反鸟──始反鸟（Ｅｏｅｎａｎｔｉｏｒｎｉｓ ｂｕｈｌｅｒｉ ｇｅｎ． ｅｔ ｓｐ． ｎｏｖ．）。在系统进化上，这一具有牙齿的反鸟介于始祖鸟和华夏鸟（Ｃａｔｈａｙｏｒｎｉｓ）之间，后者也产于中国的同一地区的早白垩世九佛常组中。这种过渡或转变突出地表现在其肩带上．新属与其他鸟类的牙齿具有共同的特征，这也说明该种齿型和其独特的植入和替换方式是所有已知中生代具牙齿鸟类的共同特征。该鸟小于始祖鸟和孔子鸟，但大于早白垩世的反鸟类。这表明在反鸟类的早期演化中，向小个体方向演化趋势所起的重要作用。

ARCHAEOPTERYX TO OPPOSITE BIRDS-MISSING LINK FROM THE MESOZOIC OF CHINA

The Confuciusornis Fauna of northeastern China has produced the oldest known enantiornithine birds-Eoenantiornis buhleri Gen. et sp. nov. A new toothed form lies between Archaeopteryx and the Early Cretaceous enantiornithine, Cathayornis,from the same region of China. The transition most marked in the shoulder girdle. The teeth of the new genus have the characteristics of other bird teeth and demonstrate that this tooth form along with its distinctive implantation and replacement is characteristic of all known toothed birds.