Enantiornithes (Aves) From The Early Cretaceous Of Western Liaoning, China

It is described that the locality of Mesozoic Enantiornithes fossils, geological age and typical stratigraphic sections in this paper, and the research history and Status quo of enantiornithes fossils at home and abroad is reviewed.18 species of enantiornithes published in China are described briefly according to existing documents and materials, and they are Sinornis santensis Paul and Rao,1992; Cathayornis yandica Zhou et al.,1992; Eoeantiornis buhleri Hou et al.,1999; Otogornis genghisi Hou,1994; Boluochia Zhengi Zhou,1995; Eoeantiornis buhleri Hou et al.,1999; Liaoxiornis delicatus Hou and Chen,1999; Protopteryx fengningensis Zhang and Zhou,2000; Longipteryx chaoyangensis Zhang et al.,2000; Longirostriornis hani Hou et al.,2004; Jibeinia luanhera Hou,1997; Vescornis hebeienis Zhang et al.,2004; Pengornis houi Zhou et al.,2008; Shanweiniao cooperorum O’CONNOR et al.,2009; Rapaxavis pani MORSCHHAUSER et al., 2009; Cathayornis chabuensis Li et al.,2008; Huoshanornis huji Wang et al.,2010; Shenqiornis mengi Wang et al.,2010.One family and three genera are established after researching skeletal features of Enantiornithes fossils specimen from west of Liaoning province in detail, which are stored in Paleontological Institute of SYNU.One family and one genus are published officially. The family is Alethoalaornithidae Li et al.,2007, including one, Alethoalaornis agitornis Li et al., 2007 and four supplementary materials, LPM00038、LPM00053、LPM00040、LPM00032. Another three genus and species are Dapingfangornis sentisorhinus Li et al.,2006; Camptodontus yangi Li et al.,2010 and Gracilornis jiugotangensis Li et al.,2011.One family and three genus and species are compared with other Enantiornithes respectively in characteristics of skeletal structure according to existing documents and materials and the features of fossils specimen. Its taxonomic position is further confirmed. Alethoalaornis agitornis Li et al.,2007 is compared with other Ornithurae of same age in skeletal system in detail, of which are Thoracic girdle, Sternum, forelimbs, Pelvic girdle and hindlimbs. Furthermore, Enantiornithes are compared briefly with Ornithurae in preying habit, body size and volation. More detailed information is provided for taxonomy of Enantiornithes in the future.The reason why Enantiornithes died out is speculated preliminarily at the end of this paper from two aspects, one of which is to discuss the reason through their occurring and earlier species’ morphological structure and evolving course, another of which is to discuss the reason why they died out at the end of Mesozoic through the unstable environment at that time.