Early diversification of birds: Evidence from a new opposite bird

A new enantiornithine bird Longipteryx chaoyangensis gen. et sp. nov. is de scribed from the Early Cretaceous Jiufotang Formation in Chaoyang, western Liaoning Province. This new bird is distinguishable from other known enanti ornithines in having uncinate processes in ribs, elongate jaws, relatively long wings and short hindlimbs, and metatarsal IV longer than metatarsals I I and III. This new bird had probably possessed (i) modern bird-like thorax which provides firm attachment for muscles and indicates powerful and acti ve respiratory ability; (ii)powerful flying ability; (iii) special adaptati on for feeding on aquatic preys; and (iv) trochleae of metatarsals I - IV a lmost on the same level, an adaptation for perching. The new bird represent s a new ecological type different from all known members of Enantiornithes. It shows that enantiornithines had probably originated earlier than the Ea rly Cretaceous, or this group had experienced a rapid radiation right after it first occurred in the early Early Cretaceous.