A New Enantiornithine Specimen From The Early Cretaceous Dabeigou Formation Of Northeastern Hebei In China

Enantiornithes is a Avian group that flourishing in Mesozoic. Enantiornithes derived from theEarly Cretaceous, and extinct during the Late Cretaceous. According to the distribution and abundanceof the fossils, the enantiornithes might have been the most abundant group among the Mesozoic birds,and the first group of birds to spread to all the continents successfully. They shows diverse ecologicaltypes, and consisting two sister clades of Mesozoic Ornithothoraces with Ornithurae. The knownfossil records suggest that since the Early Cretaceous, Enantiornithes has possessed similarmorphological characters of flight to modern birds.Herein a new Enantiornithine specimen is described. It is a small sized younger individual fromthe Early Cretaceous Dabeigou Formation in Fengning, Hebei Province. Except of some diagnosiccharacters of Enantiornithes, it has a sternum with a forked distal end of the xiphial process as inLiaoningornis longidigitrus.The limb proportions are also similar with these in Liaoningornislongidigitrus. Based on the features, the new Enantiornithine specimen is briefly referred toLiaoningornis longidigitrus. Two distally tapered and ribbon-like rectrices without barbs are preservedin the new specimen, representing a new tail type of Mesozoic birds. The further discoveries areneeded to clarify whether or not this tail type is present only in enantiorthine juveniles.