The Huajiying Formation is a geological formation in Hebei, People's Republic of China. Known for its fossils including feathered dinosaurs, the age of the formation is uncertain. It may represent an early portion of the Jehol Biota, dating to somewhere in the early Cretaceous or late Jurassic periods. It may correlate with the early Cretaceous Dadianzi Formation and parts of the Yixian Formation, with an age range between 140 and 122 Ma ago.Wang, X., O'Connor, J.K., Zhao, B., Chiappe, L.M., Gao, C. and Cheng, X. (2010). "New species of Enantiornithes (Aves: Ornithothoraces) from the Qiaotou Formation in Northern Hebei, China." Acta Geologica Sinica, 84(2): 247-256. It contains the Qiaotou Member, sometimes treated as a distinct formation.
Age and stratigraphy The Huajiying Formation contains the following members, in order from youngest to oldest:
5th Volcanic Member Guohedao Sedimentary Member 4th Volcanic Member Nianzigou Sedimentary Member 3rd Volcanic Member Qiaotou Sedimentary Member 2nd Volcanic Member Sichakou Sedimentary Member 1st Volcanic Member
The age of the formation is uncertain. Ji and colleagues suggested in 2008 that the Qiaotou Member correlates with the Dawangzhangzi bed of the Yixian Formation, dated to ~122 Ma ago by Zhou in 2006.Zhou, Z. (2006). "Evolutionary radiation of the Jehol Biota: chronological and ecological perspectives." Geological Journal, 41: 377–393. Ji et al. also suggested that the lower Sichakou Member correlates with the Dadianzi Formation, dated to 140 Ma ago by Tian and colleagues in 2003.Tian, S.G., Liu, Y.Q., Li, P.X., Pang, Q. and Niu, S. (2003). "Sequence stratigraphy of Jurassic-Cretaceous boundary strata in Luanping, Northern Hebei, China." Science in China Series D: Earth Sciences, 47(7): 607―617.
Paleobiota The faunal lists below are based on a survey of the Huajiying Formation by Jin Fan and colleagues in 2008, unless otherwise noted.Jin, F., Zhang, F.C., Li, Z.H., Zhang, J.Y., Li, C. and Zhou, Z.H. (2008). "On the horizon of Protopteryx and the early vertebrate fossil assemblages of the Jehol Biota." Chinese Science Bulletin, 53(18): 2820-2827.
Theropods Genus Species County Member Abundance Notes ImagesArchaeornithuraA. meemannaeFengningSichakou MemberA hongshanornithid ornithuromorph; the only known ornithuromorph from the Huajiying Formation. Lifestyle possibly similar to that of modern wading birds (such as plovers).CruralispenniaC. multidontaSichakou MemberAn enantiornithine. Convergently evolved many ornithuromorph features.EoconfuciusornisE. zhengiSichakou MemberA confuciusornithid pygostalian avialan. Known from two specimens. Second specimen (referred in 2017) preserves soft tissues. Previously reported from the Dabeigou Formation.EopengornisE. martiniSichakou MemberA pengornithid enantiornithine. Preserves many similarities with Pengornis, for which it is named. The oldest pengornithid."Hebeiornis""H. fengningensis"Qiaotou MemberNomen nudum/objective junior synonym of Vescornis. Some authors consider Vescornis as the synonym to this taxon, as 'Hebeiornis' was established first (1999; Vescornis named in 2004).JibeiniaJ. luanheraQiaotou Member An enantiornithine. Similar to Vescornis, potentially synonymous. Only known specimen missing. Previously reported from the Yixian Formation.JinfengopteryxJ. elegansQiaotou Member A troodontid. The genus namesake of the troodontid subfamily Jinfengopteryginae. Previously reported from the Yixian Formation.OrienantiusO. ritteriSichakou MemberA basal enantiornithine. Known from two specimens. Preservation of soft tissues best visualized under ultraviolet light.ParaprotopteryxP. gracilisQiaotou MemberA basal enantiornithine; presumably related and similar to Protopteryx. Preserves 4 long rectrices; 2 of which may be the result of artifice. Previously reported from the Yixian Formation.ProtopteryxP. fengningensisSichakou Member A basal enantiornithine. Known from five specimens. Previously reported from the Yixian Formation.ShenqiornisS. mengiQiaotou Member A bohaiornithid enantiornithine. First described member of the family.VescornisV. hebeiensisQiaotou Member A gobipterygid enantiornithine. Similar to Jibeinia, potentially synonymous. Known specimen preserves mainly impressions of bone. Named from same specimen as 'Hebeiornis'; potentially synonymous. Previously reported from the Yixian Formation. XunmenglongX. yinlianglisSichakou MemberA compsognathid. The smallest known member of the family; about the same size as the Scipionyx samniticus holotype. Had disproportionately long lower legs.
Pterosaurs Genus Species County MemberAbundance Notes Images CratonopterusC. huabei Fengning A ctenochasmatid OrnithocheiroideaIndeterminate Fengning Partial skeleton of an indeterminate ornithocheiroid
Fishes Genus Species County Member Abundance Notes ImagesLycopteraL. davidiAlso present in the Jiufotang Formation & Yixian FormationAn osteoglossomorphL. tokunagaiPeipiaosteusP. fengningensis A fish related to sturgeonsProtopsephurusP. liuiAlso present in the Jiufotang & Yixian FormationsA paddlefishYanosteusY. longidorsalisAlso present in the Yixian Formation A peipiaosteid
Invertebrates Genus Species County MemberAbundance Notes Images YanjiestheriaY. huajiyingensisWell-preserved remains and eggs. A spinicaudatan
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