specific name honouring ornithologist Alan Feduccia. The holotype, D2454, was discovered at the Sihetun locality and is kept at the Dalian Natural Museum. According to Zhang and colleagues, C. feducciai differed from other Confuciusornis species in its larger size, skeletal proportions, and a number of morphological features. The forelimb was 15% longer than the hind limb, while they were of equal length in C. sanctus. The upper end of the humerus lacked the large opening (foramen) that is characteristic for other Confuciusornis specimens. The first phalanx of the first digit was more slender. Other differences occur in the furcula, which was V-shaped; the sternum, which was broader than long; and the ischium, which was long compared to the pubis. Marguán-Lobon and colleagues, in 2011, argued that this diagnosis is problematic. The large opening in the humerus, although apparently absent in the left humerus, was clearly present in the right humerus of the holotype. Furthermore, their statistical analysis found the specimen to fall well within the continuum of variation of C. sanctus. These authors therefore proposed that C. feducciai is identical (a junior synonym) of C. sanctus. Confuciusornis jianchangensis was named in 2010 by Li Li and colleagues, based on specimen PMOL-AB00114 found at Toudaoyingzi. In contrast to most other species, which stem from the Yixian Formation, C. jianchangensis is found in the Jiufotang Formation. In 2002 Hou named the genus Jinzhouornis, but Chiappe et al. (2018) and Wang et al. (2018) showed that this genus is a junior synonym of Confuciusornis based on morphometry and examination of known confuciusornithiform specimens. Description Size Confuciusornis was about the size of a modern crow, with a total length of and a wingspan of up to . Its body weight has been estimated to have been as much as , or as little as . C. feducciai was about a third longer than average specimens of C. sanctus. Distinguishing traits Confuciusornis shows a mix of basal and derived traits. It was more "advanced" or derived than Archaeopteryx in possessing a short tail with a pygostyle (a bone formed from a series of short, fused tail vertebrae) and a bony sternum (breastbone), but more basal or "primitive" than modern birds in retaining large claws on the forelimbs, having a primitive skull with a closed eye-socket, and a relatively small breastbone. At first the number of basal characteristics was exaggerated: Hou assumed in 1995 that a