Itat Formation

Itat Formation
Stratigraphic range: Bajocian-Bathonian ~170–166 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
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 / 55.7; 89.2
Approximate paleocoordinates	58.2°N 86.7°E / 58.2; 86.7
Region	Siberia
Country	Russia
Extent	Krasnoyarsk krai, Nazarovo depression, SE West Siberian basin
Type section
Named for	Itatsky
Itat Formation (Russia) Show map of Russia Itat Formation (Krasnoyarsk Krai) Show map of Krasnoyarsk Krai

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.

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

See also

• List of dinosaur-bearing rock formations

References

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