A new ornithuromorph (Aves) with an elongate rostrum from the Jehol Biota, and the early evolution of rostralization in birds

A new species of Early Cretaceous ornithuromorph with an elongate rostrum is described from the Sihedang locality of the Lower Cretaceous Yixian Formation in north-eastern China. Like the longipterygid enantiornithines, rostral elongation in Dingavis longimaxilla gen. et sp. nov. is achieved primarily through the maxilla, whereas neornithines elongate the premaxilla and rostralization is far more extreme than observed in early birds. Notably, in...