The Frankfurt specimen of Psittacosaurus sp. (SMF R 4970) from the Early Cretaceous Jehol deposits of Liaoning (Figure S1) exhibits exceptional preservation of scale-clad integument¹. Preservation of colour patterns and countershading allowed a detailed reconstruction of this individual’s physical appearance. It was previously noted that the cloacal region was preserved², but its detailed anatomy was incorrectly reconstructed. We show here that the fine anatomy of the vent is remarkably well preserved and can be retrodeformed to illustrate its three-dimensional nature. The vent’s scale anatomy and pigmentation are distinct from adjacent body regions, and although its anatomy does not reveal much information about the ecology, or sex, of this dinosaur, it suggests possible roles for visual and olfactory signalling.

鹦鹉嘴龙的法兰克福标本。来自辽宁早白垩世热河矿床的（SMF R 4970）（图 S1）表现出对鳞片覆盖体¹的特殊保存。保留颜色图案和反阴影可以详细重建此人的外貌。先前已注意到泄殖腔区域被保留²，但其详细的解剖结构被错误地重建。我们在这里展示了通风口的精细解剖结构保存得非常好，并且可以通过逆向变形来说明其三维性质。通风口的鳞片解剖结构和色素沉着与邻近的身体区域不同，尽管它的解剖结构并没有揭示有关这种恐龙生态或性别的太多信息，但它暗示了视觉和嗅觉信号传导的可能作用。