Research On A New Specimen Of Enantiornithine From Yixian Formation In Weichang County,Hebei In China

Enantiornithines is an extinct Mesozoic natural group of birds named for the articulation of the scapula and coracoid,which are the opposite of those modern birds.The phylogenetic analysis confirms Enantiornithes and Ornithuromorpha are the sister group relationship.The age distribution of Enantiornithes was wide,from the early Cretaceous to the late Cretaceous that span the entire Cretaceous,represents the first avian lineage to undergo a large scale radiation.With the discovery of Mesozoic fossil birds,the understanding of Enantiornithes has also made remarkable progress.These fossils reveal unparalleled insights into the origin and early evolution of birds.Bohaiornithidae is the most speciesous clade in Enantiornithes.This paper describes a new fossil material of enantiornithines found in the Lower Cretaceous of Chengde Weichang,Hebei Province.A detailed study of a new specimen and Bohaiornithidae indicate that,characteristic are distinguishable from other enantiornithines by a unique combination of features in the skull,sternum,pectoral girdle and Hindlimbs.So this dissertation classifies the new specimen into Bohaiornithidae.At the same time,this paper makes a detailed comparison and discussion between the new material and Monoenantiornis sihedangia which the similar species of Bohaiornithidae.Modify some identification features,add some information of compound bone fusion.The morphology and phalangeal proportions indicated that the life habit of new fossil adapted between arboreal and cursorial locomotion.A monophyletic clade consisting of new fossil,Monoenantiornis sihedangia and Bohaiornithidae are constitute in a new comprehensive phylogenetic analysis.The new specimen preserves part of the feather intact,On the basis of previous studies,we measured the size of melanosomes,Preliminary speculated that the feathers of the new specimen are mainly black.Forelimb feathers have the same color distribution with the living birds.