封面说明：鹏鸟(Pengornis)复原图。鹏鸟是早白垩世已知体型最大的反鸟类，在此之前仅发现1件标本，即侯氏鹏鸟(Pengornis houi)的正型标本。侯氏鹏鸟兼有反鸟类和今鸟类的特征，揭示了今鸟类和反鸟类间复杂的特征演化模式。在与其进行详细的形态学对比之后，最近发现于辽宁九佛堂组的1件保存近乎完整的亚成年鸟类标本被归入鹏鸟未定种。新标本提供了之前未能良好保存的鹏鸟的其他解剖学特征，根据其保存的胸骨显示的特征，可以探讨早期鸟类胸骨的演化。详见本期胡晗等人文。(绘图：史爱娟) 　　

Cover image: the reconstruction of Pengornis. Pengornis is the largest known Early Cretaceous enantiornithine bird. The holotype of Pengornis houi is the only previously known specimen of Pengornis. Recently, a nearly complete subadult specimen was recovered from the Jiufotang Formation. Morphological comparisons between it and the holotype of Pengornis houi show that it can be referred to Pengornis, and may represent a new species but is treated as Pengornis sp. This specimen provides new information regarding the anatomy of the Pengornis genus, and the preserved sternal morphology contributes information that clarifies evolutionary trends in early birds. See details in the paper of Hu et al. (Illustrated by SHI Ai-Juan)