The Tiaojishan Formation is a geological formation in Hebei and Liaoning, People's Republic of China, dating to the middle-late Jurassic period (Callovian-Kimmeridgian stages). It is known for its exceptionally preserved fossils, including those of plants, insects and vertebrates. It is made up mainly of pyroclastic rock interspersed with basic volcanic and sedimentary rocks. Previously, the Tiaojishan Formation was grouped together with the underlying Haifanggou Formation (also known as the Jiulongshan Formation) as a single "Lanqi Formation." The Tiaojishan Formation forms a key part of the Yanliao Biota assemblage, alongside the Haifanggou Formation.
Age Using Argon–argon dating, Wang and colleagues in 2005 dated part of the Tiaojishan Formation to about 160 million years ago, the beginning of the Oxfordian stage, the first stage of the Upper Jurassic epoch. In 2006, a study by Liu and colleagues used U-Pb zircon dating to conclude that the Tiaojishan Formation correlates with the Daohugou Beds, and the complete chronological range of this shared biota dates to between 168 and 164/152 Ma ago. A subsequent study, published in 2008, refined the age range of the formation further, finding that the lower boundary of the Tiaojishan was formed 165 Ma ago, and the upper boundary somewhere between 156 and 153 Ma ago.
Climate Based on the plant life present in the Tiaojishan Formation, Wang Yongdong and colleagues determined that the climate in Liaoning during the mid Jurassic would have been subtropical to temperate, warm and humid.
Fauna Beautifully preserved fossils of dinosaurs, pterosaurs, salamanders, insects, arachnidsNotably Mongolarachne jurassica. and other invertebrates, conifers, ginkgoes, cycads, horsetails, and ferns, and even the earliest known gliding mammal (Volaticotherium) have been discovered in these rocks.The tuffaceous composition of some rock layers show that this was a volcanic area, occasionally experiencing heavy ashfalls from eruptions. The landscape then was dominated by mountain streams and deep lakes surrounded by forests of gymnosperm trees.
The forests of the Yanliao biota grew in a humid, warm - temperate climate and were dominated by gymnosperm trees. There were ginkgopsids like Ginkoites, Ginkgo, Baiera, Czekanowskia, and Phoenicopsis. There were also conifers like Pityophyllum, Rhipidiocladus, Elatocladus, Schizolepis, and Podozamites. Also, Lycopsids like Lycopodites and Sellaginellities, horsetails (Sphenopsida) like Equisetum, cycads like Anomozamites, and ferns (Filicopsida) like Todites and Coniopteris.
Fish
Fish of the Tiaojishan Formation Genus Species Location Stratigraphic position Abundance Notes Images YanliaomyzonY. occisor Liaoning A lamprey.
Salamanders
Salamanders of the Tiaojishan Formation Genus Species Location Stratigraphic position Abundance Notes Images BeiyanerpetonB. jianpingensis Liaoning ChunerpetonC. tianyiensisJeholotritonJ. paradoxusLiaoxitritonL. daohugouensisPangerpetonP. sinensis
Pterosaurs Pterosaurs of the Tiaojishan Formation Genus Species Location Stratigraphic position Abundance Notes Images ArchaeoistiodactylusA. linglongtaensisLü Junchang and Fucha Xiaohui (2011). "A new pterosaur (Pterosauria) from Middle Jurassic Tiaojishan Formation of western Liaoning, China". Global Geology Z1: 113–118. Liaoning A monofenestratan known from an incomplete skeleton with a partial skull and lower jawCascocaudaC. rongHebeiDaohugou bedOne specimenA long-tailed batrachognathine anurognathid known from a complete skeleton with preserved impressions of soft-tissue ChangchengopterusC. pani Hebei A pterodactyliform known only from a single specimen of a young juvenile, measuring in wingspan. DaohugoupterusD. delicatus Inner Mongolia One specimenPterosaur known from a partial skeleton with soft tissue impressionsDarwinopterusD. modularis Liaoning A wukongopteridD. linglongtaensis D. robustodens D. camposiLiaoningOne specimenDendrorhynchoides?D. curvidentatus?One specimenAn anurognathid; originally reported from the Yixian Formation, later suggested to be from Tiaojishan; other studies dispute thisDouzhanopterusD. zhengiLinglongtaOne specimenA non-pterodactyloid monofenestratan FenghuangopterusF. lii Liaoning A scaphognathine rhamphorhynchidJeholopterusJ. ninchengensisInner MongoliaSeveral specimensA batrachognathine anurognathid with preserved soft tissue anatomy JianchangnathusJ. robustus Liaoning A scaphognathine rhamphorhynchid known from a single fossil skeleton JianchangopterusJ. zhaoianus Liaoning A scaphognathine rhamphorhynchid known from a nearly complete skeleton with the skull preservedKunpengopterusK. sinensisLiaoningDaohugou bedThree specimensA wukongopteridK. antipollicatusLiaoning Two nearly complete specimensLiaodactylusL. primusDaxishan (Linglongta)One specimenA ctenochasmatid LuopterusL. mutoudengensis Hebei One specimenA batrachognathine anurognathid; originally classed as a species of Dendrorhynchoides; suggested to have been Early Cretaceous in agePterorhynchusP. wellnhoferiInner MongoliaDaohugou bedOne specimenA darwinopteran known from a nearly complete skeleton including preserved soft-tissue anatomyQinglongopterusQ. guoi Liaoning A rhamphorhynchine rhamphorhynchid known from only one specimenSinomacropsS. bondei HebeiDaohugou bed One specimenA long-tailed batrachognathine anurognathid known from a relatively complete skull and skeleton with soft tissue patchesWukongopterusW. liiLiaoningDaohugou bedOne specimenA wukongopterid
Dinosaurs Ornithischians Ornithischians of the Tiaojishan Formation Genus Species Location Stratigraphic position Abundance Notes Images PulaosaurusP. qinglong Qinglong One specimenThe first neornithischian described from the Yanliao Biota; known from a well-preserved, articulated, nearly complete skeleton including soft tissue impressions and gut contents. TianyulongT. confuciusiLiaoningA heterodontosaur initially reported as being from the Early Cretaceous Jehol group; preserved with feather-like filaments Theropods Theropods of the Tiaojishan Formation Genus Species Location Stratigraphic position Abundance Notes Images AnchiornisA. huxleyi Liaoning Several specimensAn anchiornithid at first believed to be a troodontid; analysis of the fossils has enabled scientists to determine what colors the animal may have exhibited in life AurornisA. xui Liaoning One specimenAn anchiornithid roughly the size of a modern pheasantCaihongC. jujiHebeiYanliao BiotaOne specimenAn anchiornithid known from an adult specimen measuring 400 mm in body length; analysis of the fossils has enabled scientists to determine what colors the animal may have exhibited in life EosinopteryxE. brevipenna Liaoning One specimenAn anchiornithid at first believed to be a troodontid, known from a single complete skeleton of a subadult or adult individualEpidexipteryxE. huiInner MongoliaDaohugou bedsOne specimenA scansoriopterygid known from a well-preserved partial skeleton, measuring 10 inches in length (17.5 inches including the incomplete tail feathers)PedopennaP. daohugouensisInner MongoliaDaohugou bedsOne specimenAn anchiornithid known only from a foot and ankle with soft tissue impressionsScansoriopteryxS. heilmanniLiaoningExact provenance of type specimen unknown, most likely from the Daohugou BedsOne or two specimensA sparrow-sized scansoriopterygid known from one or two juvenile specimens SerikornisS. sungei Liaoning One specimenAn anchiornithid with plumulaceous-like feathersXiaotingiaX. zhengiLiaoningOne specimen An anchiornithid originally thought to be either a dromaeosaur or a troodontidYiY. qiHebeiDaohugou bedsOne specimenA gliding scansoriopterygid, weighing about
Lizards
Lepidosaurs (lizards and relatives) of the Daohugou Beds Genus Species State Abundance Notes ImagesHongshanxiH. xieiLiaoningComplete specimen and counterpartFamily unknownUnnamed lizardInner MongoliaOne specimenA new lizard with relatively short forelimbsUnnamed lizardInner MongoliaOne specimenA lizard with long hind limbs and a narrow body
Mammals Mammals of the Tiaojishan Formation Genus Species Location Stratigraphic position Abundance Notes ImagesAgilodocodonA. scansoriusInner MongoliaDaohugou bedA shrew-sized, arboreal docodontid ArboroharamiyaA. jenkinsi Liaoning One specimenAn arboreal, prehensile-tailed euharamiyid haramiyidan estimated to have weighed about 354 gramsA. fuscus A preserved skeleton with fur An arboreal, prehensile-tailed euharamiyid haramiyidan with a specific furDocofossorD. brachydactylusHebeiOne specimenA docodontid specialized for a subterranean burrowing lifestyle JuramaiaJ. sinensis Liaoning One specimenA small, shrew-like therian which weighed around ; it may be a stem-eutherian, but this classification has been questioned by someMaiopatagiumM. furculiferum MegaconusM. mammaliaformis Inner Mongolia Daohugou bedOne specimenAn eleutherodontid haramiyidan thought to have been a herbivore that lived on the groundMicrodocodonM. gracilisDaohugou bedA tegotheriid docodontanQishouQ. jizantangEuharamiyidaRugosodonR. eurasiaticusLiaoningDaxishan siteOne specimen An omnivorous paulchoffatoid multituberculate; one of the oldest-known multituberculates It is estimated to have weighed between 65 and 80 grams, about that of an average chipmunk.VolaticotheriumV. antiquumInner MongoliaDaohugou bedOne specimenA gliding, flying squirrel-like volaticotherian eutriconodont with a specialized gliding membraneVilevolodonV. diplomylosA gliding eleutherodontid haramiyidanXianshouX. linglong, X. songaeA gliding euharamiyidan
Arthropods
The following orders are represented in the formation; Ephemeroptera, Odonata, Plecoptera, Blattodea, Orthoptera, Hemiptera, Neuroptera, Coleoptera, Hymenoptera, and Diptera.
An indeterminate aeshnoid (insect) species is known from Liaoning.
Arthropods of the Daohugou Beds Genus Species State Abundance NotesImagesAhirmoneuraA. neimengguensisInner MongoliaA tangle-veined flyArchirhagioA. striatusArchisargid fliesA. zhangiInner MongoliaArchisargusA. spuriveniusArchisargid fliesA. strigatusCalosargusC. (Calosargus) antiquusArchisargid fliesC. (C.) bellusC. (C.) daohugouensisC. (C.) haniC. (C.) tenuicellulatusC. (C.) validusC. (Pterosargus) sinicusInner MongoliaDarwinulaD. impudicaLiaoningAn ostracodD. magnaLiaoningAn ostracodD. sarytirmenensisLiaoningAn ostracodDaohugocorixaD. vulcanicaA water boatmanFuyousF. gregariousA mayflyEoplectreurysE. gertschi1 Specimen A plectreurid spiderHomocatabrycusH. liuiA schizophorid flying water beetleJurassinemestrinusJ. orientalisInner MongoliaA Nemestrinoid flyMenopraesagusM. explanatusSchizophorid flying water beetlesM. oxycerusM. grammicusMeoslovaM. daohugouensisAn archisargid flyMostovskisargusM. portentosusInner MongoliaArchisargid fliesM. signatusInner MongoliaShantousS. lacustrisA mayflySinoschizalaS. daraniA schizophorid flying water beetle
Other invertebrates
Genus Species Province Stratigraphic Position Abundance Notes ShaanxiconchaS. cliovata Liaoning A bivalve
Flora Survey based on Wang et al. 2006 unless otherwise noted.
Bennettitales Cycad-like plants, the most abundant plant group in the formation. 27 species in 11 genera.
Bennettitales of the Tiaojishan Formation Genus Species Location Stratigraphic position Abundance Notes ImagesAnomozamites BennetticarpusCycadolepisJacutiellaPteriophyllumPtilophyllumWilliamsoniaWilliamsoniellaZamiophyllumZamites
Ginkgoales Prehistoric ginkgo trees, common, with 11 species present in 6 genera.
Ginkgoales of the Tiaojishan Formation Genus Species Location Stratigraphic position Abundance Notes ImagesGinkgo IxostrobusPhoenicopsisSphenobaieraSolenites
Pinophyta Conifers, 5 species present in 4 genera.
Pinophytans of the Tiaojishan Formation Genus Species Location Stratigraphic position Abundance Notes ImagesPityocladus PityophyllumPodizamitesSchizolepisYuccites
Pteridophyta