The Yixian Formation () is a geological formation in Jinzhou, Liaoning, People's Republic of China, that spans about 1.6 million years during the early Cretaceous period (Barremian-Aptian stage). It is known for its diverse fossils, listed below. These include dinosaurs, pterosaurs, mammals, amphibians, fish, and various invertebrates.
The Yixian Formation is divided into the following subunits: (ages from Zhong et al., 2021 unless otherwise noted)
Upper Yixian (124.1 Ma) ("Jingangshan Bed") ("Dawangzhangzi Bed") Upper Lava Unit Jianshangou Unit (125.46 Ma) Lower Lava Unit Lujiatun Unit (125.76–125.68 Ma)
Sauropods Genus Species County Member Material NotesImagesDongbeititanD. dongiBeipiaoJianshangou BedPartial postcraniaA basal titanosauriformcf. Euhelopuscf. E. sp.Lujiatun BedIsolated teethA basal titanosauriformLiaoningotitanL. sinensisNearly complete skeletonA basal titanosauriformRuixiniaR. zhangiBeipiaoA partial articulated skeletonA somphospondylan titanosauriformSauropoda spp.Lujiatun & Jianshangou BedsIsolated vertebrae and teethOne or more species of sauropods, possibly titanosaurs, have been recovered from the Yixian Formation, though most remain undescribed
Ornithischians The dinosaurs listed below were compiled in a survey by Xu and Norell in 2006, unless otherwise noted. Ankylosaurs Genus Species County Member Material Notes ImagesLiaoningosaurusL. paradoxusYixianDawangzhangzi Bed"Partial skull [and] skeleton.""Table 17.1," in Weishampel, et al. (2004). Page 367. A small ankylosaur Ceratopsians Genus Species County Member MaterialNotes ImagesLiaoceratopsL. yanzigouensisBeipiaoLujiatun Bed"[Two] nearly complete skulls, juvenile to adult.""Table 22.1," in Weishampel, et al. (2004). Page 480.A ceratopsian PsittacosaurusP. lujiatunensisBeipiaoLujiatun & Jianshangou BedsThousands of specimens in the Lujiatun Bed, somewhat less common in the Jianshangou BedA ceratopsian
Ornithopods Genus Species County Member Material NotesImagesBolongB. yixianensisJianshangou BedA nearly complete skeleton. An iguanodontian ornithopodChangmianiaC. liaoningensisLujiatun BedTwo nearly complete skeletonsA basal ornithopod that may have dug burrowsHaolongH. dongiJianchangJianshangou UnitNearly complete skeleton with preserved integumentA hadrosauroid ornithopodJeholosaurusJ. shangyuanensisBeipiaoLujiatun Bed"Skull with associated vertebrae and hindlimb, skull with cervical vertebrae.""Table 18.1," in Weishampel, et al. (2004). Page 395. An ornithopodJinzhousaurusJ. yangiYixianDawangzhangzi Bed"Nearly complete skull and skeleton.""Table 19.1," in Weishampel, et al. (2004). Page 416.An ornithopod
Theropods The dinosaurs listed below were compiled in a survey by Xu and Norell in 2006, unless otherwise noted.
Avialans
Genus Species County Member Material NotesImagesAbitusavisA. liiNingcheng"Nearly complete skeleton."ArchaeorhynchusA. spathulaDawangzhangzi BedAn early, advanced short-tailed bird (ornithuran)Changchengornis"Table 11.1," in Weishampel, et al. (2004). Page 211.C. hengdaoziensisJianshangou Bed"Nearly complete skeleton."A confuciusornithidConfuciusornisC. chuonzhousJunior synonym of Confuciusornis sanctusC. dui"Table 11.1," in Weishampel, et al. (2004). Page 212.Jianshangou Bed"[Two] skeletons."C. feducciaiJianshangou BedC. sanctusJianshangou and Dawangzhangzi Beds"Hundreds of complete skeletons."A primitive short-tailed bird (pygostylian), also present in the Jiufotang FormationC. suniaeJunior synonym of Confuciusornis sanctusDalingheornisD. liweiiDawangzhangzi BedAn EnantiornithineEoenantiornisE. buhleriJianshangou Bed"Nearly complete skeleton.""Table 11.1," in Weishampel, et al. (2004). Page 213.An entantiornithineEogranivoraE. edentulataDawangzhangzi Bed"Nearly complete skeleton with skull"An ornithuromorphAn ornithuromorph; previously regarded as Yixian, horizon reassigned to the Jiufotang Formation by Ju et al., 2021JinzhouornisJ. yixianensisJianshangou BedA pygostylian, a junior synonym of Confuciusornis sanctusHou, L.H., Zhou, Z.H., Zhang, F.C., et al. (2002). "Mesozoic Birds from Western Liaoning." In China Shenyang, China: Liaoning Science and Technology Publishing HouseJ. zhangjiyingiaJianshangou BedJunior synonym of C. sanctusJixiangornisJ. orientalisJianshangou BedA basal avialan, also present in the Jiufotang FormationHongshanornisH. longicrestaJianshangou and Dawangzhangzi BedsFour specimensAn ornithuromorphJibeiniaJ. luaheraPreviously regarded as Yixian, horizon reassigned to the Huajiying Formation by Jin et al., 2008.LiaoningornisL. longidigitrisLujiatun Bed"Partial skeleton.""Table 11.1," in Weishampel, et al. (2004). Page 214.An enantiornithine.LiaoxiornisL. delicatusDawangzhangzi BedConsidered a nomen dubium because the name is based on remains of a hatchling entantiornithine and cannot be confidently matched with the adult form.LingyuanornisL. parvusDawangzhangzi BedJunior objective synonym of Liaoxiornis delicatus, a nomen dubium.LongicrusavisL. houiDawangzhangzi BedAn ornithuromorphLongirostravisL. hanibed unknownAn enantiornithineProtopteryxP. fengningensisPreviously regarded as Yixian, horizon reassigned to the Huajiying Formation by Jin et al., 2008.MirusavisM. parvusPartial skeleton.An immature female enantiornithine preserved with medullary bone tissue.SapeornisS. chaoyangensisNearly complete skeleton.A subadult omnivoropterygid with preserved feathers.ShanweiniaoS. cooperorumDawangzhangzi BedAn enantiornithine.VescornisV. hebeiensisPreviously regarded as Yixian, horizon reassigned to the Huajiying Formation by Jin et al., 2008.YixianosaurusY. longimanusDawangzhangzi BedAn anchiornithidZhongornisZ. haoaeDawangzhangzi BedA primitive avialan with a short but non-pygostylian tail
Compsognathids
Genus Species County Member Material NotesImagesHuadanosaurusH. sinensisDawangzhangzi BedA nearly complete specimen missing the feet and end of the tailA compsognathidHuaxiagnathusH. orientalisBeipiaoJianshangou BedA compsognathidSinocalliopteryxS. gigasBeipiaoJianshangou BedA large compsognathidSinosauropteryxS. lingyuanensisDawangzhangzi BedA nearly complete specimenA compsognathidS. primaBeipiao & LingyuanJianshangou & Dawangzhangzi BedsFour nearly complete specimens"Table 4.1," in Weishampel, et al. (2004). Page 76.A compsognathid. The first non-avian dinosaur found with feather impressions.S.? sp.BeipiaoJianshangou BedOne specimen (GMV 2124) with partial skull, postcrania, and preserved feathersAn unnamed coelurosaur originally described as a specimen of Sinosauropteryx, later suggested to be a new genus and species, probably a tyrannosauroid.
Dromaeosaurs Genus Species County Member Material NotesImagesChangyuraptorC. yangiJianchangA complete articulated specimen with extensive feathering.A dromaeosauridGraciliraptorG. lujiatunensisBeipiaoLujiatun BedAn incomplete specimen.A dromaeosauridSinornithosaurusS. haoianaYixianDawangzhangzi BedMight be a junior synonym of Sinornithosaurus millenii.S. milleniiBeipiaoJianshangou BedThree specimens with skulls and postcrania, two with preserved feathers."Table 10.1," in Weishampel, et al. (2004). Page 198. Feathered integument is also preserved.Azuma, (2005). The Flying Dinosaurs: Fukui Prefectural Dinosaur Museum. 118 pp.A dromaeosaurid, the first ever found with feather impressions.TianyuraptorT. ostromiLingyuanDawangzhangzi BedA dromaeosaurid ZhenyuanlongZ. suniJianchangOne nearly complete skeleton with preserved feathers, including long tail feathers and large wing feathers.A dromaeosaurid Zhongjianosaurus Z. yangi Lingyuan A partial skeleton includes an arm, legs, vertebrae, ribs, and most of the tail. A microraptorian dromaeosaurid with very long legs. Unnamed dromaeosauridSpecimen NGMC 91LingyuanDawangzhangzi BedComplete specimen with feather imprintsA juvenile dromaeosaurid that may be a specimen of Sinornithosaurus millenii. Informally nicknamed "Dave".
Ornithomimosaurs
Genus Species County Member Material NotesImagesHexingH. qingyiBeipiaoLujiatunA primitive ornithomimosaurShenzhousaurusS. orientalisBeipiaoLujiatun Bed"Articulated skull and incomplete skeleton.""Table 5.1," in Weishampel, et al. (2004). Page 138.A primitive ornithomimosaur
Oviraptorosaurs
Genus Species County Member Material NotesImagesCaudipteryxC. dongiBeipiaoJianshangou BedOne partial postcranium with feather imprints"Table 8.1," in Weishampel, et al. (2004). Page 166.An oviraptorosaurC. zouiBeipiaoJianshangou BedCommon, only over a small regionC. sp. IncisivosaurusI. gauthieriBeipiaoLujiatun BedA skull and partial cervicalAn oviraptorosaurNingyuansaurusN. wangiComplete skeleton with feather impressions.An oviraptorosaurProtarchaeopteryxP. robustaBeipiaoJianshangou Bed"Nearly complete skull and skeleton, at least [two] individuals.""Table 11.1," in Weishampel, et al. (2004). Page 216.A possible relative of IncisivosaurusSimilicaudipteryxS. yixianensisTwo specimensAn oviraptorosaur, also present in the Jiufotang FormationXingtianosaurusX. ganqiLiaoningDakangpu BedOne nearly complete specimen (IVPP V13390), minus the headAn oviraptorosaur
Therizinosaurs
Genus Species County Member Material NotesImages ImagesBeipiaosaurusB. inexpectusBeipiaoJianshangou BedIncomplete skeleton with integument"Table 7.1," in Weishampel, et al. (2004). Page 152.A therizinosaur KayrasaurusK. changliensisBeipiaoNearly complete skeleton including the skull; missing the hindlimbsA therizinosaur JianchangosaurusJ. yixianensisJianchangA nearly complete juvenile specimen with feather impressionsA therizinosaur
Troodontids Genus Species County Member Material NotesImagesDaliansaurusD. liaoningensisBeipiaoLujiatun BedA very complete specimen.A troodontidJianianhualongJ. tengiBeipiaoDawangzhangzi BedA very complete specimen with feather impressions.A troodontidLiaoningvenatorL. currieiBeipiaoA very complete specimen.A troodontidMeiM. longBeipiaoLujiatun BedA small troodontid fossilized in a sleeping positionSinovenatorS. changiiBeipiaoLujiatun BedThree specimens with partial skulls and postcrania."Table 9.1," in Weishampel, et al. (2004). Page 185. Hundreds of additional specimens known but undescribed.A troodontidSinusonasusS. magnodensBeipiaoLujiatun BedA troodontid Undescribed deinonychosaur/possible troodontidDawangzhangzi BedOne specimen with feather imprintsA possible troodontid. Undescribed troodontidSpecimen CAGS-IG01-004Lujiatun BedSkull and partial skeletonA troodontid similar to Mei.
Tyrannosaurs and other theropods
Genus Species County Member Material NotesImagesDilongD. paradoxusBeipiaoLujiatun & Jianshangou BedRareA tyrannosauroidGrallatorlower Jianshangou BedFootprints belonging to the Grallator form taxon, belonging to a small theropod. Of known Yixian theropods, the footprints most closely match Caudipteryx.RaptorexR. kriegsteiniA tyrannosaurid, probably from higher Mongolian strata.ScansoriopteryxS. heilmanniInitially reported from the Dawangzhangzi Bed, probably from the Daohugou Beds instead.YutyrannusY. hualiUnknownThree nearly complete skeletons of various agesA large tyrannosauroidUnnamed theropodNot yet describedYixianLujiatun BedPartial post-cranial skeletonA possible allosauroid
Pterosaurs The pterosaurs listed below were compiled in a survey by Wang and Zhou in 2006, unless otherwise noted.