中国辽宁义县早白垩世燕鸟一新种

辽宁锦州义县早白垩世义县组发现了一种新型燕鸟(Yanornis)化石.该新型化石具有燕鸟的典型特征,如齿骨直且约占头骨全长的2/3、每侧约含20枚牙齿,颈椎细长,异凹型.愈合荐椎包括9枚脊椎,前肢约为后肢长的1.1倍.近端脚趾较其它趾节长和粗壮.然而,该新型化石部分特征又不同于燕鸟的模式种——马氏燕鸟(Yanornis martini),如其肱骨三角肌脊强烈发育,约为肱骨长度的一半.尺骨、桡骨及手部近等长,均长于肱骨.耻骨联合部较短,与尾综骨等长,不到耻骨长度的1/6.腓骨较长,约为股骨长度的4/5,约为胫跗骨长度的2/3.跗跖骨较短并完全愈合,不及胫跗骨长度一半.根据该新型化石的独特性及其与义县鸟、松岭鸟和马氏燕鸟的特征对比,笔者建立了燕鸟一新种——国章燕鸟(Yanornis guozhangisp.nov.).此外,国章燕鸟(新种)颈部还保存有3条鱼化石,这一特殊现象为研究燕鸟的生活习性和发育模式提供了重要信息.

A new species of Yanornis (Aves: Ornithurae) from the Lower Cretaceous strata of Yixian, Liaoning Province

A nearly complete specimen of Yanornis was recently discovered from the Early Cretaceous Yixian Formation at Yixian, Jinzhou City, Liaoning Province. This specimen shows typical characteristics of Yanornis, such as the straight dentary, about 2/3 the length of skull, with about 20 teeth on each side. The cervicals are long and heterocoelous. The synsacrum is composed of 9 sacrals. The length ratio of forelimb to hindlimb is about 1.1. The proximal pedal phalanges are longer and more robust than the distal ones. However, the new specimen is different from the type species-Yanornis martini, by having the following unique characteristics: the humerus has a large and strong deltoid crest, which is almost half the length of the shaft. The pubic symphysis is short, with the same length as the pygostyle, and is less than 1/6 the length of the pubis. The fibular is long, about 4/5 the length of femur and 2/3 the length of the tibiotarsus. The tarsometatarsus is short and completely fused, less than half the length of the tibiotarsus. This specimen can be erected as a new species of Yanornis-Yanornis guozhangi sp. nov., on the basis of its unique characteristics and a comparison with Yixianornis grabaui, Songlingornis linghensis and Yanornis martini. It is notable that three fish fossils were preserved along the neck of Yanornis guozhangi sp. nov., which provides important information for studying the living habit and growth pattern of Yanornis.