Description Of A New Enantiornithine Bird From The Early Cretaceous Of Western Liaoning, China

Western Liaoning is located in the northeast part of China.Its non-marine sedimentary strata, especially in Jiufutang Formation and Yixian Formation of Early Cretaceous,yield a mass of notable fossils including abounded enantiornithine birds which providing important evidence for the study of the origin and early evolution of birds.This essay contains mainly three parts:The first part is a synoptic review of enantiomithes.In this part,a brief introduction of researching history,of fossil enantiomithes,present situations and outlook is made.And the morphology,evolution,and phylogeny are reviewed.The second part is a detail description of a new enantiornithine bird Huoshanornis huji gen.et sp.nov from the Early Cretaceous Jiufotang Formation in Chaoyang,western Liaoning Province.The enantiornithine status of Huoshanornis is indicated by some unambiguous synapomorphies.These include a V-shaped furcula with a long hypocleidum,a coracoid with a convex lateral margin,a slender and reduced metatarsusâ…£,a sternum with a parabolic anterior margin and a distally expanded caudolateral processes.This bird exhibits characteristics that distinguish from other known enantiornithines in possessing quite reduced alular digit,unreduced second phalanx of minor digit,undeveloped major metacarpal,special caudal processes of sternum with one pair of laterocaudal processes and two pairs of mediocaudal processes and exceptionally curved and powerful pedal claws.The third part is a comparison between Huoshanornis and other enantiomithes.The manual characters,stemum characters,flight ability and ecology are discussed.The features of Huoshanornis suggest that it has possessed the ability of fligh but its ability of flapping flight is relatively weak,it possesses strong perching capability and show again that enantiornithines had experienced a significant differentiation in Early Cretaceous.