Soft tissue preservation in fossil birds provides a rare window into their anatomy, function, and development. Here, we present an exceptionally-preserved specimen of Confuciusornis which, through Laser-Stimulated Fluorescence imaging, is identified as preserving a disassociated rhamphotheca. Reconstruction of the in vivo position of the rhamphotheca validates the association of the rhamphotheca with two previous confuciusornithid specimens while calling that of a third specimen into question. The ease of dissociation is discussed and proposed with a fourth specimen alongside finite element analysis as evidence for preferential soft-food feeding. However, this proposition remains tentative until there is a better understanding of the functional role of beak attachment in living birds. Differences in post-rostral extent and possibly rhamphotheca curvature between confuciusornithids and modern birds hint at developmental differences between the two. Together, this information provides a wealth of new information regarding the nature of the beak outside crown Aves.

化石鸟类的软组织保存为它们的解剖结构、功能和发育提供了一个难得的窗口。在这里，我们展示了一个保存完好的孔子鸟标本通过激光刺激荧光成像，它被鉴定为保存了分离的rhamhotheca。重组鼠尾草的体内位置验证了鼠尾纤与两个先前的孔鸟标本的关联，同时对第三个标本的标本提出了质疑。与作为优先软食喂养的证据一起的第四个样本与有限元分析一起讨论并提出了分离的容易性。然而，在更好地了解喙附着在活鸟类中的功能作用之前，这个提议仍然是暂定的。孔鸟科和现代鸟类之间的后喙范围和可能的rhamphotheca曲率的差异暗示了两者之间的发育差异。一起，