A primitive confuciusornithid bird from China and its implications for early avian flight

Confuciusornithids, lived from 120–125 million years ago, form a basal bird group and include the oldest birds with horny beaks. Here we describe Eoconfuciusornis zhengi, gen. et sp. nov. from the Early Cretaceous Dabeigou Formatio (131 Ma) in Fengning, Hebei Province, northern China. It represents a new and, more primitive than other known, member of this group and extends the lifespan of this family to 11 Ma, the longest of any known Early Cretaceous avian lineages. Furthermore, Eoconfuciusornis and its relatives present many osteological transformations, such as the size increase of the deltopectoral crest of the humerus and the keel of the sternum, apparently an adaptation toward improved flight in the evolution of the Confuciusornithidae.