未成熟羽毛在早白垩世热河鸟类生物群幼年反鸟类中的首次报道
邹晶梅, 福雅曼, 王敏, 郑晓廷

First report of immature feathers in juvenile enantiornithines from the Early Cretaceous Jehol avifauna
Jingmai K. O’CONNOR, Amanda FALK, WANG Min, ZHENG Xiao-Ting
Fig. 2 Illustration of the stages in feather development
A. pin feather, early immature stage; B. blood-quill, mid-immature stage; C. late immature stage; D. mature feather