Confuciusornis is a genus of basal crow-sized avialan from the Early Cretaceous Period of the Yixian and Jiufotang Formations of China, dating from 125 to 120 million years ago. Like modern birds, Confuciusornis had a toothless beak, but closer and later relatives of modern birds such as Hesperornis and Ichthyornis were toothed, indicating that the loss of teeth occurred convergently in Confuciusornis and living birds. It was thought to be the oldest known bird to have a beak, though this title now belongs to an earlier relative Eoconfuciusornis. It was named after the Chinese moral philosopher Confucius (551–479 BC). Confuciusornis is one of the most abundant vertebrates found in the Yixian Formation, and several hundred complete specimens have been found. History of discovery In November 1993, the Chinese paleontologists Hou Lianhai and Hu Yoaming of the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) at Beijing, visited fossil collector Zhang He at his home in Jinzhou, where he showed them a fossil bird specimen that he had bought at a local flea market. In December, Hou learned about a second specimen, which had been discovered by a farmer named Yang Yushan. Both specimens were found in the same locality in Shangyuan, Beipiao. In 1995, these two specimens, as well as a third one, were formally described as a new genus and species of bird, Confuciusornis sanctus, by Hou and colleagues. The generic name combines the philosopher Confucius with Greek ὄρνις (ornis), "bird". The specific name means "holy one" in Latin and is a translation of Chinese 圣贤 (shèngxián), "sage," again in reference to Confucius. The first discovered specimen was designated the holotype and catalogued under the specimen number IVPP V10918; it comprises a partial skeleton with skull and parts of the forelimb. Of the other two skeletons, one (paratype, IVPP V10895) comprises a complete pelvis and hind limb, and the other (paratype, IVPP V10919–10925) a fragmentary hind limb together with six feather impressions attached to both sides of the tibia (shin bone). It was soon noted that the two paratype specimens only comprise bones that are unknown from the holotype, and that this lack of overlap makes their referral to the species speculative. Only the discovery of a great number of well-preserved specimens shortly after had confirmed that the specimens indeed represent a single species. Together with the early mammal Zhangheotherium, which was discovered at around the same time, Confuciusornis was