The Jinju Formation (), also known as the Dongmyeong Formation () in some literature is a Lower Cretaceous formation in South Korea.Jinju Formation in the Paleobiology Database Lithology of the Jinju Formation could be distinguished from overlying and underlying formations by lack of red beds in the entire formation.
The depositional age of this formation spans from approximately 112.4 ± 1.3 to 106.5 million years ago (early Albian) based on detrital zircon U-Pb dating. It predominantly consists of black shale, with sandstone packets, deposited in a fluvial-lacustrine setting. The entire paleoenvironment of the Jinju Formation is interpreted as a balanced-fill lake basin, with deltas and streams.
A diverse arthropod fauna, including isopods, spiders, and insects, is known from the formation. Other notable fossils known from the formation include several freshwater fishes, ostracods, and plants. This formation has also "attracted global ichnological attention" for the variety of important ichnofossils. Columnar and rod-shaped stromatolites have also been found here.
Fossil content
Plants
Based on plant fossil records, the Jinju Flora is interpreted as a temperate intermontane savannah, due to mountain barriers blocking moisture. The assemblage was dominated by stress-tolerant, low-diversity flora adapted to the arid conditions or to localized waterlogged niches. Not only restricted to the Jinju Formation, but the entire floral diversity was relatively low throughout the entire Gyeongsang Supergroup. Palynofossil records also suggest the Jinju Formation was overall arid.
Unnamed plant remains include 3 different types of unidentified ferns, at least 2 types of seed cones, a conifer pollen cone, detached conifer seed cone scales, a connate bractate organ of unknown affinity, and at least 9 different types of diaspores, including winged forms and likely fleshy forms.
+Plants of the Jinju FormationGenusSpeciesRegionMemberMaterialNotesImageEquisetumE. cf. burchardti HorsetailE. sp.EquisetitesE. naktongensisHorsetailHausmanniaH. sp. Dipteridaceae ferncf. Klukiacf. K. sp. Schizaeaceae fernRuffordiaR. sp.Schizaeaceae fernOnychiopsisO. elongataleptosporangiate fernCladophlebisC. sp. A Fern, family unknown.C. sp. BC. sp. CC. sp. DC. sp. ESphenopterisS. sp. AS. sp. BS. sp. CSectilopterisS. sp. AS. sp. BPseudofrenelopsisP. sp. Scale- and awl-leaved Cheirolepidiaceae coniferPlatycladiumP. sp. Scale- and awl-leaved conifer, family unknown. Cupressinocladus sp. described in Kim 2009 might allied with this taxon.GeinitziaG. sp. A Divergent-leaved Geinitziaceae conifer G. sp. BPagiophyllumP. sp. A Scale- and awl-leaved conifer, family unknown.P. sp. BElatocladusE. sp. A Divergent-leaved conifer, family unknown.E. sp. BPityophyllumP. sp. A Divergent-leaved coniferP. sp. BBrachyphyllumB. japonicum Scale- and awl-leaved conifer, family unknown.B. sp. AB. sp. BB. sp. CCupressinocladusC. sp. A Scale- and awl-leaved conifer. The presence of this taxon indicates that a mixed type of the Tetori-Type and the Ryoseki-Type flora existed in this formation.C. sp. BPodozamitesP. sp. Broadleaf conifer, family unknown.KrassiloviaK. sp. Seed cones Krassiloviaceae conifer cf. Elatides cf. E. sp. Seed cones Cupressaceae conifer Pityospermum P. sp. A diaspore Pinaceae coniferDesmiophyllumD. sp. Non-conifer broadleaf gymnosperm, family unknown. Doylea D. sp. Bifurcated seed-bearing cupulate unit Doylealean gymnosperm Jarudia J. sp. Seed-bearing cupulate unit with 2 distal seeds Doylealean gymnosperm Umaltolepis U. sp. Seed-bearing capulate units Possible Ginkgoopsid
Spiders +Spiders of the Jinju FormationGenusSpeciesRegionMemberMaterialNotesImageKorearachneK. jinjuSacheonlikely to be a lycosoidKoreamegopsK. samsikiJinju and Sacheona lagonomegopidJinjumegopsJ. dalingwateriJinjua lagonomegopidMygalomorphaeIndeterminateSacheonAraneomorphaeIndeterminatePalpimanoideaIndeterminate"Cribellate Entelegynae" "species 1"Jinju "species 2"
Insects
Odonata +Dragonflies and damselflies of the Jinju FormationGenusSpeciesRegionMemberMaterialNotesImageHemeroscopus H. baissicusSacheon, Gunwi and JinjuBoth nymphs and adultsH. jinjuensisSacheonTwo wingsKoreapodagrionK. coloratusJinjuIsolated wings
Dermaptera +Earwigs of the Jinju FormationGenusSpeciesRegionMemberMaterialNotesImagecf. Pygidicranoideaindeterminate
Orthoptera +Orthopterans of the Jinju FormationGenusSpeciesRegionMemberMaterialNotesImagePanorpidiumP. spicaA member of Elcanidae
Dictyoptera +Dictyopterans of the Jinju FormationGenusSpeciesRegionMemberMaterialNotesImageCretophotinaC. smidovaeA member of MantodeaJuramantisJ. jinjuensisJ. geongonrigamBubosaB. petrarosaA member of BlattidaeNeoblattellaN. coockrockA member of EctobiidaePerlucipectaP. jinjuicolaA member of MesoblattinidaeP. cyclopicaP. majorPraeblattellaP. tinctoriaP. decolorMongoloblattaM. koreaensisArchimesoblattaA. basopictaSpinaeblattina S. variabilittaJinjublattaJ. cascadaerrorumStictolampraS. baqueuiiA member of BlaberidaeHolocompsaH. scleropteraA member of CorydiidaeIoouoonoolI. taktobyboloAsioblattaA. jeongchonensisA member of RaphidiomimidaeCameloblattaC. immaculataTayphoonoblattaT. correntiniElongatoblatta E. minsukiAnoA. aleA member of LiberiblattinidaeBrutalistaB. masivnyBlattulaB. pessimusestfinisA member of BlattulidaeElisamaE. baekiE. simplex E. gwanghyeoni OcellonlattulaO. gyongsangensisVrtulaV. jinjuensisV. gwanghyeonensis MementoM. futuriA member of CaloblattinidaeSclerotermesS. samsikiJinjuA termite known only from an isolated wing, uncertain placementUmenocoleusU. minimusA member of UmenocoleidaePseudoblattapterixP. weoniPetropterixP. koreaensisP. oculataP. nikdyviacBlattapterixB. reticulataAlienopterusA. imposterA member of AlienopteridaeRecyklovanyR. koltocCaputoraptorC. gangguIndeterminate5 indeterminate taxa
Hemiptera +Hemipterans of the Jinju FormationGenusSpeciesRegionMemberMaterialNotesImageCorixidaeindeterminateSacheonNot fully describedJinjucixiusJ. fuiJinju and GunwiA member of CixiidaeJinjupopovinaJ. eosahwaeJinjuA member of Yuripopovinidae
Hymenoptera Hymenopterans of the Jinju FormationGenusSpeciesRegionMemberMaterialNotesImageKorehelorus K. jinjuensis JinjuA parasitic wasp belonging to the family HeloridaeHanguksyntexis H. haeretica A sawfly belonging to the family AnaxyelidaeCretosphecium C. jinjuensisA wasp belonging to the family AngarosphecidaeGhilarella G. jinjuensisSepulcidae waspMeiaghilarella M. stanislawlemi
Raphidioptera +Snakeflies of the Jinju FormationGenusSpeciesRegionMemberMaterialNotesImageMesoraphidiaM. koreensisA member of MesoraphidiidaeM. phantasma
Neuroptera Lacewings of the Jinju FormationGenusSpeciesRegionMemberMaterialNotesImageTachinymphesT. koraiensisA member of the family Mesochrysopidae.AraripeneuraA. asiaticaA member of AraripeneuridaeAraripenymphesA. koreicusA member of Cratosmylidae
Coleoptera +Beetles of the Jinju FormationGenusSpeciesRegionMemberMaterialNotesImageCoptoclavaC. spinosaJinju and GunwiLarval remains abundant; Adult remains relatively rareA member of the extinct family Coptoclavidae.MegalithomerusM. magolhalmiiA member of ElateridaeKoreagrypnusK. jinjuCryptocoelusC. minimusCretosajaC. jinjuensisA member of SilphidaeNotocupesN. premerisA member of ArchostemataAsianaA. paxBrochocoleusB. sacheonensisA member of Ommatidae B. cf. punctatus OmmaO. sp.ZygadeniaZ. cornigeraLaetopsiaL. leeiA member of Hydrophiloidea L. cf. hydraneoides L. sp.CretotaeniaC. pallidaPsacodromeusP. rectaA member of TrachypachidaeNecronectulusN. lazarus
Diptera +Flies of the Jinju FormationGenusSpeciesRegionMemberMaterialNotesImageBuccinatormyiaB. gangnamiA member of the family Zhangsolvidae. Named after Gangnam Style, the famous K-Pop hit song
Crustaceans
Isopoda +Isopods of the Jinju FormationGenusSpeciesRegionMemberMaterialNotesImageArchaeoniscusA. coreaensisSacheon and JinjuA freshwater occurrence of the genus Archaeoniscus
Ostracoda +Ostracods of the Jinju FormationGenusSpeciesRegionMemberMaterialNotesImageScabriculocyprisS. yanbianensisJinjuCyprideaC. jinjuriaJinju C. khandaeJinju and SacheonC. samesiJinjuMongolocyprisM. kohiJinjuLycopterocyprisL. cf. celsaJinjuCandonaC. sp.JinjuDjungaricaD. sp.JinjuRhinocyprisR. sp.ChilgokPreviously assigned to as Ilyocypris sp.
Spinicaudata +Clam shrimps of the Jinju FormationGenusSpeciesRegionMemberMaterialNotesImageYanjiestheriaY. kyongsangensisY. chekiangensisY. cf. wannanensisY. jinjuensisY. sp.
Vertebrates Source: Actinopterygii +Fishes of the Jinju FormationGenusSpeciesRegionMemberMaterialNotesImageWakinoichthysW. aokiiMultiple complete skeletonsAn osteoglossiformJinjuichthysJ. cheongiJinjuArticulated skeletonsA possible ichthyodectiform, though this classification remains controversialAlbuliformesindeterminateSinamiaS. sp.Articulated incomplete tailAn amiiformLepidotesL. sp.Articulated skeleton, missing the anterior part of the headLargest fish found in this formation, reaching in total length.ElopiformesindeterminateA small fish, reaching in total length.
Reptiles +Reptiles of the Jinju FormationGenusSpeciesRegionMemberMaterialNotesImageCrocodyliformes indet.Goryeonga right mandibleTitanosauriformes indet.Sacheon and GoryeongteethA tooth from Sacheon was initially suggested to be of Asian Brachiosaurid by Lim, Martin and Baek (2001), but Barrett et al. (2002) and Choi & Lee (2017) consider it to be indeterminate titanosauriform. Meanwhile, another tooth from Goryeong was suggested to be of Diplodocoidea by Yun et al. (2007), but Choi and Lee (2017) also considered it indeterminate titanosauriform.Pterodactyloidea indet.GoryeongteethWhile the KPE 40001 suggested to be of Boreopterid origin by Choi & Lee (2017), Yun (2021) and Yun (2024) consider them to be Anhanguerian instead based on the morphological disparity from Boreopteridae and the results of two-dimensional geometric morphometric analyses.
Mollusks
Bivalvia +Bivalves of the Jinju FormationGenusSpeciesRegionMemberMaterialNotesImagePlicatounioP. naktongensisGoryeongNagdongiaN. soniGoryeongTrigonioidesT. jaehoiGoryeong
Gastropoda +Gastropods of the Jinju FormationGenusSpeciesRegionMemberMaterialNotesImageBrotiopsisB. kobayashi Dominant gastropod of the formationThiaraT. sp.ViviparusV. sp.
Ichnofossils Unnamed ichnofossils from the Jinju Formation include Ornithopod tracks and Caddisfly bioherms.