Itat Formation
Geological formation in western Siberia, Russia
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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.[1] 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.[2] The formation is noted for bearing significant coal reserves, with large open pit coal mines extracting lignite from the unit currently in operation.
Sub-unitsLower, Middle and Upper members
UnderliesTyazhin Formation
OverliesIlan Formation
| Itat Formation | |
|---|---|
| Stratigraphic range: Bajocian-Bathonian ~ | |
| Type | Geological formation |
| Sub-units | Lower, Middle and Upper members |
| Underlies | Tyazhin Formation |
| Overlies | Ilan Formation |
| Thickness | Several hundred metres |
| Lithology | |
| Primary | Sandstone, mudstone, coal |
| Other | Siltstone |
| Location | |
| Coordinates | 55.7°N 89.2°E |
| Approximate paleocoordinates | 58.2°N 86.7°E |
| Region | Siberia |
| Country | Russia |
| Extent | Krasnoyarsk krai, Nazarovo depression, SE West Siberian basin |
| Type section | |
| Named for | Itatsky |
  Itat Formation (Russia)  Itat Formation (Krasnoyarsk Krai) | |
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.[3] 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.[1] The deposit is located on the South Eastern margin of the West Siberian basin[4]
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.[5] The fossils were largely obtained by screenwashing of the debris. 10-15 tons of material have been processed so far.
Paleobiota
Taken from[2] unless otherwise noted.
Fish
| Fish of the Itat Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Abundance | Notes | Images |
| Hybodus | Indeterminate | Berezovsk coal mine | Upper Member | Partial tooth | ||
| Acipenseriformes | Indeterminate | Berezovsk coal mine | Upper Member | Scales | ||
| Amiiformes | Indeterminate | Berezovsk coal mine | Upper Member | "Abundant vertebrae, jaws and vomer fragments, as well as isolated teeth, and numerous isolated rhomboidal scales" | ||
| Dipnoi | Indeterminate | Berezovsk coal mine | Upper Member | One complete upper tooth plate, several tooth plate fragments | ||
| Palaeonisciformes | Undescribed | Berezovsk coal mine | Upper Member | Many partial skeletons | Similar to Palaeoniscinotus and Pteroniscus | |
Amphibians
| Amphibians of the Itat Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Abundance | Notes | Images |
| ?Eodiscoglossus[6] | Indeterminate | Berezovsk coal mine | Upper Member | Atlantal centrum | Frog | |
| Kiyatriton[7] | K. krasnolutskii | Berezovsk coal mine | Upper Member | Dentary, atlantes, trunk vertebrae and fragmentary cranial and postcranial bones | Formerly known as "Berezovsk salamander B"; genus also known from Early Cretaceous Ilek Formation. | Crown group Salamander |
| Urupia[8] | U. monstrosa | Berezovsk coal mine | Upper Member | Dentary, femur, an incomplete atlas, an anterior fragment of the left dentary, and fragments of trunk vertebrae | Estimated length of 480-560 centimetres | Stem-Salamander |
| Egoria [9] | E. malashichevi | Berezovsk coal mine | Upper Member | Atlantal centra, trunk vertebrae | Formerly known as "Berezovsk salamander A" Possibly neotenic | Stem-Salamander |
Turtles
| Turtles of the Itat Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Abundance | Notes | Images |
| Annemys | A. variabilis[10] | Berezovsk coal mine | Upper Member | Thousands of isolated bones and several fragmented specimens, including three partial braincases and larger fragments of connected shell parts[11] | Xinjiangchelyid | |
| Testudines | Indeterminate | Berezovsk coal mine | Upper Member | Likely one or two taxa distinct from Annemys.[11] | ||
Lepidosauromorphs
| Lepidosauromorphs of the Itat Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Abundance | Notes | Images |
| Lepidosauromorpha | Indeterminate | Berezovsk coal mine | Upper Member | Several fragments of dentaries and maxillae | Basal form similar to Marmoretta | |
| Scincomorpha | Indeterminate | Berezovsk coal mine | Upper Member | Fused premaxillae and two dentary fragments additionally several fragmentary maxillae and dentaries | Two distinct taxa, one of which is two times smaller than the other. | |
Choristoderes
| Choristoderes of the Itat Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Abundance | Notes | Images |
| Cteniogenys | Indeterminate | Berezovsk coal mine | Upper Member | Skull roof bones, maxillary and dentary fragments, vertebrae, ribs | ||
Pterosaurs
| Pterosaurs of the Itat Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Abundance | Notes | Images |
| ?Rhamphorhynchidae | Indeterminate | Berezovsk coal mine | Upper Member | Numerous isolated teeth and very rare bone fragments | ||
Crocodyliforms
| Crocodyliforms of the Itat Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Abundance | Notes | Images |
| Goniopholididae[12] | Indeterminate | Berezovsk coal mine | Upper Member | Several dozens of isolated teeth, osteoderms, and a few cranial fragments | ||
Dinosaurs
| Dinosaurs of the Itat Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Abundance | Notes | Images |
| Kileskus[13] | K. aristotocus | Berezovsk coal mine | Upper Member | Holotype 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[14] | Proceratosaurid |  |
| Heterodontosauridae | Indeterminate | Berezovsk coal mine | Upper Member | Isolated maxillary and dentary teeth | ||
| Mamenchisauridae[15] | Indeterminate | Berezovsk coal mine | Upper Member | Numerous isolated teeth and two platycoelous posterior caudal vertebrae | Sauropod | |
| Stegosauria[16] | Indeterminate | Berezovsk coal mine | Upper Member | Fragmentary skeletons of at least two individuals |  | |
Mammaliamorphs
| Mammaliamorphs of the Itat Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Abundance | Notes | Images |
| Amphibetulimus[17] | A. krasnolutskii | Berezovsk coal mine | Upper Member | Dentary fragments, canine and upper molar[18] | Alternately considered an amphitheriid or a cladotherian | |
| Amphitherium | Indeterminate | Berezovsk coal mine | Upper Member | Upper and lower molars and an edentulous dentary fragment | An amphitheriid | |
| Anthracolestes[19] | A. sergeii | Berezovsk coal mine | Upper Member | Isolated teeth and edentulous dentary fragments | A dryolestid | |
| Hutegotherium[20] | H. yaomingi | Berezovsk coal mine | Upper Member | A docodont | ||
| Itatodon[21] | I. tatarinovi | Berezovsk coal mine | Upper Member | Either a docodont or a member of the family Shuotheriidae | ||
| Maiopatagium | M. sibiricum[22] | Berezovsk coal mine | Upper Member | A euharamiyidan | ||
| Sharypovoia[22] | S. arimasporum, S. magna | Berezovsk coal mine | Upper Member | A euharamiyidan | ||
| Simpsonodon[20] | S. sibiricus | Berezovsk coal mine | Upper Member | A docodont | ||
| "Sineleutherus"[23] | "S." issedonicus | Berezovsk coal mine | Upper Member | A haramiyidan, now believed to represent a number of different euharamiyidan taxa.[22] | ||
| Stereognathus[24] | Indeterminate | Berezovsk coal mine | Upper Member | Upper and lower postcanine teeth | A tritylodontid | |
| Tagaria[5] | T. antiqua | Berezovsk coal mine | Upper Member | Isolated premolar and two molars | A multituberculate | |
| Tashtykia[5] | T. primaeva | Berezovsk coal mine | Upper Member | Isolated premolars and incisors | A multituberculate | |
| Eutriconodonta[25] | Indeterminate | Berezovsk coal mine | Upper Member | One large tooth and several tooth fragments | A large tooth similar to those of Gobiconodon | |
| Multituberculata | Indeterminate | Berezovsk coal mine | Upper Member | Molariforms | ||
Insects
Numerous insect species are known from the Kubekovo village locality located within the upper member of the formation.[26]
| Insects of the Itat Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Abundance | Notes | Images |
| Epiosmylus | Epiosmylus longus | Osmylid lacewing | ||||
| Mesosmylina | Mesosmylina sibirica | |||||
| Kubekius | Kubekius multiramosus | |||||
| Thaumatomerobius | Thaumatomerobius mirabilis | Saucrosmylid lacewing | ||||
| Archizelmira | Archizelmira jarzembowskii | Archizelmirid fly | ||||
| Protanyderus | P. invalidus | Tanyderidae fly | ||||
| Boreomerope | B. antiqua | Meropeidae scorpionfly | ||||
| Itaphlebia | Itaphlebia completa, Itaphlebia jeniseica, Itaphlebia multa, Itaphlebia reducta | Nannochoristid scorpionfly | ||||
| Eublattula | E. curvinervis | A cockroach | ||||
| Mesobittacus | M. kubekovensis | hangingfly | ||||
| Eoptychoptera | E. maxima, E. modica, E. paramaculata | Ptychopteridae fly | ||||
| Eoptychopterina | E. glabra | |||||
| Proptychopterina | Proptychopterina amota, Proptychopterina handlirschi, Proptychopterina yeniseica | |||||
| Crenoptychoptera | Crenoptychoptera antica, Crenoptychoptera defossa | |||||
| Palaeoperissomma | P. collessi | Perissommatidae fly | ||||
| Prohyperoscelis | Prohyperoscelis jurassicus | Canthyloscelidae fly | ||||
| Microdiplatys | Microdiplatys perfectus | Protodiplatyidae earwig | ||||
| Cicadocoris | Cicadocoris admotus, Cicadocoris frater | Progonocimicidae bug | ||||
| Olgamartynovia | Olgamartynovia nana | |||||
| Locustopsis | Locustopsis picta | Locustopsidae orthopteran | ||||
| Tinaphis | Tinaphis sibirica | Szelegiewicziidae aphid | ||||
| Tarantogus | Tarantogus obscurus, Tarantogus opiparus, Tarantogus sibiricus | Mesopsychidae scorpionfly | ||||
| Blattula | Blattula aberrans, Blattula sibirica | Blattulid cockroach | ||||
| Kemobius | Kemobius lux | Archijassid leafhopper | ||||
| Kisa | Kisa fasciata | |||||
| Kubecola | Kubecola guttatus | |||||
| Necrotaulius | Necrotaulius kubekovi | Necrotauliidae caddisfly | ||||
| Orthophlebia | Orthophlebia obunca | Orthophlebiidae scorpionfly | ||||
Flora
| Flora of the Itat Formation[1] | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Abundance | Notes | Images |
| Lycopodites | Indeterminate | Club moss | ||||
| Equisetites | E. asiaticus, E. cf. lateralis | Stem-horsetail | ||||
| Coniopteris | C. hymenophylloides, C. simplex, C. cf. maakiana | Fern | ||||
| Cladophlebis | C. denticulata | Fern | ||||
| Gonatosorus | G. cf mrassiensis | Fern | ||||
| Todites | T. cf. princeps | Fern | ||||
| Lobifolia | Indeterminate | Fern | ||||
| Rhizomopteris | Indeterminate | Fern | ||||
| Ginkgo | Indeterminate, G. ex gr. insolita | Genus extant | ||||
| Podozamites | Indeterminate | Conifer | ||||
| Sphenobaiera | Indeterminate | Ginkgoales | ||||
| Stenorachis | S. cf. scanicus | Gymnosperm | ||||
| Czekanowskia | Indeterminate | Czekanowskiales | ||||