摘要
记述发现于辽宁省朝阳县原家洼村中生代地层中的反鸟类一新科:真翼鸟科(Alethoalaornithidae fam.nov.)。由于该科鸟类具有肩胛骨直,第1、2指仍有爪,腓骨和胫跗骨不愈合,趾骨不太钩曲等特征,将真翼鸟科归入华夏鸟目(Cathayornithiformes)。真翼鸟科的特有特征包括:吻尖,齿少,牙齿退化的趋势明显,腕掌骨基本形成,乌喙骨远端宽,肱骨近端具明显的气窝,尾综骨长,跗蹠骨末端三趾骨等长且滑车末端基本处于同一水平面,趾骨爪长,不甚钩曲等。通过对新材料和其它早期鸟类的对比认为,反鸟类的灭绝不仅有自身构造的原因,还有它们所生活的生态环境多变的原因。
In this paper we report a new family of enantiornithiness from the Early Cretaceous of western Liaoning. Alethoalaornithidae Fam. nov. The new family is assigned to Cathayornithiformes based on similar length of trochlea at the distal end of tarsometatarsus. The main features of Alethoalaornithidae are listed below： sharp beak; few and rudimentary teeth; carpometacarpus developed basically ;coracoid broad at the distal end; obvious foramina at the proximal end of humerus; long pygostyle; three digits of tarsometatarsus being the same in length with trochlea at the same height;and long claws,with no curves.
The birds of the new family can be compared with enantiornithine birds in general morphology. It is important for us to understanding the evolution of the enantiornithine birds. Besides, we can infer that the their extinction is not only because of the conservative morphological structure itself but also the frequent changes of their living environment.
Description of new genus and species
Class Aves Linnaeus, 1758
Subclass Enantiornithes Walker, 1981
Order Cathayornithiformes Zhou et al., 1992
Family Alethoalaornithidae faro. nov.
Diagnosis Long and sharper beak, a few teeth, general two pairs, at last three pairs; cervical heterocoelous; furcula process thin and long, its length equal to clavicles ramus; sternum carina processes well developed; humerus pneumatic foramina well preserved, having deep capital groove; metacarpal formed; with rudimentary manual digit claws, small and weak, two only; trochlea having same length at the distal end of tarsometatarsus; claw of digit very long, and longer than any pedal phalange.
Genus Alethoalaornis gen. nov.
Type species Alethoalaornis agitornis gen. et sp. nov.
Etymology ＂ Aletho＂ Latin, means true; ＂-alo＂ Latin, wing. Diagnosis Same as the family.
Alethoalaornis agitornis gen. et sp. nov.（Text-fig. 2, figs. 1-5） Holotype LPM （Liaoning Palaeontologic Museum） 00009, a complete individual （P I ）. The specimen stored in Shenyang Normal University.
Paratype LPM 00038.
Other specimens LPM 00032; LPM 00040 and LPM 00053. Type locality Yuanjiawa, Dapingfan, Chaoyang County, western Liaoning. Etymology ＂ agito＂ Latin, agile; ＂-rnis ＂ bird suffix.
Diagnosis As for the family.
Comparison and discussion Comparing Alethoalaornis with other early enantiornithines birds from western Liaoning, we no liced that the pectoral girdle, coracaid, scapula and pelvis of the enantiornithine birds are the same as Enantiornis from the Upper Cretaceous of Argentina except the much changed of furcula shape. In other words, Enantiornith occurred ranging from Late Jurassic to Early Cretaceous, which did not become extinct until Late Cretaceous. The pectoral girdle pelvis shape had not beer distinctly changed during several tens of million years. These features may be main factors that enantiornithine birds could not continue to live in the Cenozoic. Besides ,frequent environment changes are also one of important factors. In the irmonograph entitled 《Standard Sections of Tuchengzi Stage and Yixian Stage and their Stratigraphy, Palaeontology and Tectonic- Volcanic Actions》, Wang Wu-li et al. （2004） also investigated the relation between fossil organismus and environment, we agree with their ecological interpretations of the Late Jurassic to Early Cretaeous in western Liaoning-northern Hebei, and that the volcanic activities might have effected greatly the occurrence, development and extinction of biotas. They could either couse organisms suddenly death, or provide favourable environment for organisms＂ living and developing. The birds of the ＂ Jehol Biota＂ would have lived and multiplied in such dynamic environment.
Stratigraphic horizon The lower part of the Jiufotang Formation, Lower Cretaceous.
出处
《古生物学报》
CAS
CSCD
北大核心
2007年第3期365-372,共8页
Acta Palaeontologica Sinica
基金
现代古生物学和地层学国家重点实验室(中国科学院南京地质古生物研究所)基金(06311)
生物地质与环境地质教育部重点实验室基金(BGEG0601)
辽宁省教育厅科研基金(20060805)联合资助
关键词
真翼鸟
反鸟
演化
灭绝
辽西
Alethoalaornithidae, enantiornithines, evolution, extinction, western Liaoning
