The Amisan Formation () is an Late Triassic geologic formation in Boryeong, South Korea. Fossil records from this formation include plants, insects, and fish remains.
Geology The Amisan Formation in the Chungnam Basin overlies the Hajo Formation and underlies the Jogyeri Formation. It is subdivided into five zones based on its lithology, lower sandstone, lower shale, middle sandstone, middle shale, and upper sandstone zones. Depositional environments of the lower and middle shale zones of the Amisan Formation are thought to be lacustrine settings.
The depositional age of the Nampo Group including the Amisan Formation is debated, but plant genera Lobatannularia from the Amisan Formation, and Sphenophyllum from the Baegunsa Formation, which overlies the Amisan Formation and the Jogyeri Formation suggests that the Upper Triassic spans to the Baegunsa Formation. Also, conchostracan fossils and some insect fossils support the Triassic origin of the Amisan Formation.
Fossil content Most of the fossils from the Amisan Formation are from the lower shale zone and the middle shale zone. Flora +Flora of the Amisan FormationGenusSpeciesRegionMemberMaterialNotesImageTaeniopterisT. eurychoron T. mungyeongensis Ferns
+Ferns of the Amisan FormationGenusSpeciesRegionMemberMaterialNotesImageNeocalamitesN. carrereiCladophlebisC. nebbensisLobatannulariaL. sp.ChiropterisC. sp.EquisetitesE. kimi E. gaehwariensis E. deltodon
Bennettitales +Bennettitales of the Amisan FormationGenusSpeciesRegionMemberMaterialNotesImageAnomozamitesA. baegunsaensisPterophyllumP. seongjuriense P. daecheonenseWeltrichiaW. sp.
Gymnosperms +Gymnosperms of the Amisan FormationGenusSpeciesRegionMemberMaterialNotesImagePodozamites P. lanceolatus P. var. genuinea P. schenki P. nampoensisAnthrophyopsisA. sp.DrepanozamitesD. sp.BaieraB. cf. furcataCycadocarpidiumC. sp.CtenozamitesC. meogbangensisLeptostrobusL. myeongamensis
Bivalves +Bivalves of the Amisan FormationGenusSpeciesRegionMemberMaterialNotesImageMargaritiferaM. cf. isfarensis Conchostracans +Conchostracans of the Amisan FormationGenusSpeciesRegionMemberMaterialNotesImageEuestheriaE. kawasakii E. shimamuraiCyclestherioidesC. rampoensisSphaerestheriaS. koreanica Insects +Insects of the Amisan FormationGenusSpeciesRegionMemberMaterialNotesImageTurbidapsycheT. dobrokhotovaeA mesopsychid scorpionfly; originally assigned to the genus Mesopsyche.SiberioperlidaeIndeterminateStoneflies.PlatyperlaP. sp.BaleyopterygidaeIndeterminateHallakkungisH. amisanusA palaeontinid.TennentsiaT. koreanaA cicadomorph.SanmaiS?. zetavenaA tettigarctid.MagnatitanM. jongheoniA titanopteran.KoreaphlebiaK. iussradiaeA triadophlebiomorph odonatopteran.KoreatriassothemisK. elongatusA parazygopteran odonatopteran.?IsophlebiopteraIndeterminateA possible Isophlebioptern nymph. Referred as 'Samarura-type' in paper.ShurabiaS. taewaniA Geinitziid polyneopteran.
Vertebrates +Vertebrates of the Amisan FormationGenusSpeciesRegionMemberMaterialNotesImageHiascoactinusH. boryeongensisA redfieldiiform actinopterygian.MegalomatiaM. minimaA basal actinopterygian.
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