The Itat Formation (Russian: итатская свита) is a geologic formation in western Siberia. It was deposited in the Bajocian to Bathonian ages of the Middle Jurassic. Dinosaur remains are among the fossils that have been recovered from the formation, including the proceratosaurid Kileskus, as well as fish, amphibians, mammals and many other vertebrates. The formation is noted for bearing significant coal reserves, with large open pit coal mines extracting lignite from the unit currently in operation.
Lithology The lower section of the formation is around 50–130 m thick, and consists of light grey sandstones with gravel, siltstone and rare coal beds. At the Dubinino locality, the 50 m exposed section of the upper part of the formation shows an irregular rhythmic alteration of fine grained sandstone, siltstone and mudstone and coal seams typically a few tens of cm's but up to several meters thick. The deposit is located on the South Eastern margin of the West Siberian basin
Locality Most of the fossils were found in the overburden of Berezovsk coal mine[ru], which is located in southern Krasnoyarsk Krai (Sharypovsky District) near the border with Kemerovo Oblast. The deposit is stratigraphically located in the upper member of the formation. The fossiliferous level of the locality is located above thick (> 50 m) coal seams and consists of unconsolidated silt and sand, which were deposited on an alluvial plain. Due to the fluvial origin of the sediment the remains are disarticulated and often are water worn, though they are mostly well preserved, which suggests they had not been significantly transported. The fossils were largely obtained by screenwashing of the debris. 10-15 tons of material have been processed so far.
Paleobiota Taken from unless otherwise noted.
Fish Fish of the Itat FormationGenusSpeciesLocationStratigraphic positionAbundanceNotesImagesHybodusIndeterminateBerezovsk coal mineUpper MemberPartial toothAcipenseriformesIndeterminateBerezovsk coal mineUpper MemberScalesAmiiformesIndeterminateBerezovsk coal mineUpper Member"Abundant vertebrae, jaws and vomer fragments, as well as isolated teeth, and numerous isolated rhomboidal scales"DipnoiIndeterminateBerezovsk coal mineUpper MemberOne complete upper tooth plate, several tooth plate fragmentsPalaeonisciformes UndescribedBerezovsk coal mineUpper MemberMany partial skeletonsSimilar to Palaeoniscinotus and Pteroniscus
Amphibians Amphibians of the Itat FormationGenusSpeciesLocationStratigraphic positionAbundanceNotesImages?EodiscoglossusIndeterminateBerezovsk coal mineUpper MemberAtlantal centrumFrogKiyatritonK. krasnolutskiiBerezovsk coal mineUpper MemberDentary, atlantes, trunk vertebrae and fragmentary cranial and postcranial bonesFormerly known as "Berezovsk salamander B"; genus also known from Early Cretaceous Ilek Formation.Crown group SalamanderUrupiaU. monstrosaBerezovsk coal mineUpper MemberDentary, femur, an incomplete atlas, an anterior fragment of the left dentary, and fragments of trunk vertebraeEstimated length of 480-560 centimetresStem-SalamanderEgoria E. malashichevi Berezovsk coal mineUpper MemberAtlantal centra, trunk vertebraeFormerly known as "Berezovsk salamander A" Possibly neotenicStem-Salamander
Turtles Turtles of the Itat FormationGenusSpeciesLocationStratigraphic positionAbundanceNotesImagesAnnemysA. variabilisBerezovsk coal mineUpper MemberThousands of isolated bones and several fragmented specimens, including three partial braincases and larger fragments of connected shell partsXinjiangchelyidTestudinesIndeterminateBerezovsk coal mineUpper MemberLikely one or two taxa distinct from Annemys.
Lepidosauromorphs Lepidosauromorphs of the Itat FormationGenusSpeciesLocationStratigraphic positionAbundanceNotesImagesLepidosauromorphaIndeterminateBerezovsk coal mineUpper MemberSeveral fragments of dentaries and maxillaeBasal form similar to MarmorettaScincomorphaIndeterminateBerezovsk coal mineUpper MemberFused premaxillae and two dentary fragments additionally several fragmentary maxillae and dentariesTwo distinct taxa, one of which is two times smaller than the other.
Choristoderes Choristoderes of the Itat FormationGenusSpeciesLocationStratigraphic positionAbundanceNotesImagesCteniogenysIndeterminateBerezovsk coal mineUpper MemberSkull roof bones, maxillary and dentary fragments, vertebrae, ribs
Pterosaurs Pterosaurs of the Itat FormationGenusSpeciesLocationStratigraphic positionAbundanceNotesImages?RhamphorhynchidaeIndeterminateBerezovsk coal mineUpper MemberNumerous isolated teeth and very rare bone fragments
Crocodyliforms Crocodyliforms of the Itat FormationGenusSpeciesLocationStratigraphic positionAbundanceNotesImagesGoniopholididaeIndeterminateBerezovsk coal mineUpper MemberSeveral dozens of isolated teeth, osteoderms, and a few cranial fragments
Dinosaurs Dinosaurs of the Itat FormationGenusSpeciesLocationStratigraphic positionAbundanceNotesImagesKileskusK. aristotocusBerezovsk coal mineUpper MemberHolotype description: "premaxilla, maxilla, a mandible fragment, and several limb bone parts"; referred material includes cervical and caudal vertebrae and numerous isolated teeth, as well as a fibula Proceratosaurid HeterodontosauridaeIndeterminateBerezovsk coal mineUpper MemberIsolated maxillary and dentary teethMamenchisauridaeIndeterminateBerezovsk coal mineUpper MemberNumerous isolated teeth and two platycoelous posterior caudal vertebraeSauropodStegosauriaIndeterminateBerezovsk coal mineUpper MemberFragmentary skeletons of at least two individuals
Mammaliamorphs Mammaliamorphs of the Itat FormationGenusSpeciesLocationStratigraphic positionAbundanceNotesImagesAmphibetulimusA. krasnolutskiiBerezovsk coal mineUpper MemberDentary fragments, canine and upper molarAlternately considered an amphitheriid or a cladotherianAmphitheriumIndeterminateBerezovsk coal mineUpper MemberUpper and lower molars and an edentulous dentary fragmentAn amphitheriidAnthracolestesA. sergeiiBerezovsk coal mineUpper MemberIsolated teeth and edentulous dentary fragmentsA dryolestidHutegotheriumH. yaomingiBerezovsk coal mineUpper MemberA docodontItatodonI. tatarinoviBerezovsk coal mineUpper MemberEither a docodont or a member of the family ShuotheriidaeMaiopatagiumM. sibiricumBerezovsk coal mineUpper MemberA euharamiyidanSharypovoiaS. arimasporum, S. magnaBerezovsk coal mineUpper MemberA euharamiyidanSimpsonodonS. sibiricusBerezovsk coal mineUpper MemberA docodont"Sineleutherus""S." issedonicusBerezovsk coal mineUpper MemberA haramiyidan, now believed to represent a number of different euharamiyidan taxa.StereognathusIndeterminateBerezovsk coal mineUpper MemberUpper and lower postcanine teethA tritylodontidTagariaT. antiqua Berezovsk coal mineUpper MemberIsolated premolar and two molarsA multituberculateTashtykiaT. primaeva Berezovsk coal mineUpper MemberIsolated premolars and incisorsA multituberculateEutriconodontaIndeterminateBerezovsk coal mineUpper MemberOne large tooth and several tooth fragmentsA large tooth similar to those of GobiconodonMultituberculataIndeterminateBerezovsk coal mineUpper MemberMolariforms
Insects Numerous insect species are known from the Kubekovo village locality located within the upper member of the formation. Insects of the Itat FormationGenusSpeciesLocationStratigraphic positionAbundanceNotesImagesEpiosmylusEpiosmylus longusOsmylid lacewingMesosmylinaMesosmylina sibiricaKubekiusKubekius multiramosusThaumatomerobius Thaumatomerobius mirabilisSaucrosmylid lacewingArchizelmira Archizelmira jarzembowskiiArchizelmirid flyProtanyderusP. invalidusTanyderidae flyBoreomeropeB. antiquaMeropeidae scorpionflyItaphlebiaItaphlebia completa, Itaphlebia jeniseica, Itaphlebia multa, Itaphlebia reductaNannochoristid scorpionflyEublattulaE. curvinervisA cockroachMesobittacus M. kubekovensishangingflyEoptychoptera E. maxima, E. modica, E. paramaculataPtychopteridae flyEoptychopterinaE. glabraProptychopterina Proptychopterina amota, Proptychopterina handlirschi, Proptychopterina yeniseicaCrenoptychopteraCrenoptychoptera antica, Crenoptychoptera defossaPalaeoperissomma P. collessiPerissommatidae flyProhyperoscelisProhyperoscelis jurassicusCanthyloscelidae flyMicrodiplatysMicrodiplatys perfectusProtodiplatyidae earwigCicadocorisCicadocoris admotus, Cicadocoris fraterProgonocimicidae bugOlgamartynoviaOlgamartynovia nanaLocustopsisLocustopsis pictaLocustopsidae orthopteranTinaphisTinaphis sibiricaSzelegiewicziidae aphidTarantogus Tarantogus obscurus, Tarantogus opiparus, Tarantogus sibiricusMesopsychidae scorpionflyBlattula Blattula aberrans, Blattula sibiricaBlattulid cockroachKemobiusKemobius lux Archijassid leafhopperKisaKisa fasciataKubecolaKubecola guttatusNecrotaulius Necrotaulius kubekoviNecrotauliidae caddisflyOrthophlebiaOrthophlebia obuncaOrthophlebiidae scorpionfly
Flora Flora of the Itat FormationGenusSpeciesLocationStratigraphic positionAbundanceNotesImagesLycopoditesIndeterminateClub mossEquisetitesE. asiaticus, E. cf. lateralisStem-horsetailConiopterisC. hymenophylloides, C. simplex, C. cf. maakianaFernCladophlebisC. denticulataFernGonatosorusG. cf mrassiensisFernToditesT. cf. princepsFernLobifoliaIndeterminateFernRhizomopterisIndeterminateFernGinkgoIndeterminate, G. ex gr. insolitaGenus extantPodozamitesIndeterminateConiferSphenobaieraIndeterminateGinkgoalesStenorachisS. cf. scanicusGymnospermCzekanowskiaIndeterminateCzekanowskiales
See also List of dinosaur-bearing rock formations
References