辽宁西部早白垩世九佛堂组热河鸟类一新属种

A new jeholornithiform identified from the Early Cretaceous Jiufotang Formation in western Liaoning

辽宁朝阳早白垩世九佛堂组发现了一种新型热河鸟类化石。该化石不仅具有热河鸟类的典型特征,如尾椎由约28枚未愈合的椎体组成,中后部尾椎前后方向明显拉长;前颌骨无牙齿;齿骨后缘较直,靠近吻端腹侧明显膨大等,同时具有不同于其他已知热河鸟类的独具特征组合,如肱骨三角肌脊相对不发育;第三掌骨较直,与第二掌骨间距较小;后肢第一趾爪最大;尾椎脉弧、关节突不发育等。根据该化石的独特性及与其他热河鸟类特征对比研究,笔者建立了热河鸟类新属、新种:直掌内蒙鸟(Neimengornis rectusmim gen.et sp.nov.)。直掌内蒙鸟(新属、新种)的发现进一步丰富了热河鸟类的属种类群,为研究这一类群的形态特征和属种分异等提供了新的化石证据。

A new specimen of jeholornithiform was identified from the Early Cretaceous Jiufotang Formation in Chaoyang of Liaoning Province.This specimen shows typical characters of Jeholornithiformes,such as the long bony tail composed of about 28 free caudal vertebrae,the middle and posterior caudal vertebrae elongated antero-posteriorly,the edentulous premaxilla,and the dentary with a straight ventral margin posteriorly and a robust anterior end expanded ventrally.It differs from all other jeholornithiforms in the following unique combination of features:the relatively undeveloped deltopectoral crest of the humerus,the straight third metacarpal,which forming a small gap with the second metacarpal,the largest hallux ungula,and the undeveloped chevrons and zygapophyses of the caudal vertebrae.On the basis of unique characteristics and comparisons with other jeholornithiforms,a new genus and species(Neimengomis rectusmim gen.et sp.nov.) were erected.The identification of Neimengomis redusmim further enriches the diversity of jeholornithiforms and sheds new light on understanding the morphology and classification of this clade.