Itat Formation
{{Short description|Geological formation in western Siberia, Russia}}
{{Infobox rockunit
| name = Itat Formation
| image =
| caption =
| type = Geological formation
| age = Bajocian-Bathonian
~{{fossil range|170|166}}
| period = Bathonian
| prilithology = Sandstone, mudstone, coal
| otherlithology = Siltstone
| namedfor = Itatsky
| namedby =
| region = Siberia
| country = {{flag|Russia}}
| coordinates = {{coord|55.7|N|89.2|E|display=inline,title}}
| paleocoordinates = {{coord|58.2|N|86.7|E|display=inline}}
| unitof =
| subunits = Lower, Middle and Upper members
| underlies = Tyazhin Formation
| overlies = Ilan Formation
| thickness = Several hundred metres
| extent = Krasnoyarsk krai, Nazarovo depression, SE West Siberian basin
| area =
| map = {{Location map+ | Russia#Russia Krasnoyarsk Krai
| relief = 1
| width = 250
| float = center
| places =
{{Location map~ | Russia#Russia Krasnoyarsk Krai
| lat_deg = 55.7
| lon_deg = 89.2
| mark = Green pog.svg
| marksize = 10
}}
}}
| map_caption =
}}
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.{{Cite journal|last1=Ivantsov|first1=S. V.|last2=Bystritskaya|first2=L. I.|last3=Krasnolutskii|first3=S. A.|last4=Lyalyuk|first4=K. P.|last5=Frolov|first5=A. O.|last6=Alekseev|first6=A. S.|date=September 2016|title=Middle Jurassic continental biota and paleolandscape in the Dubinino locality (Sharypovo area, Krasnoyarsk krai)|journal=Stratigraphy and Geological Correlation|volume=24|issue=5|pages=486–502|doi=10.1134/s0869593816050038|bibcode=2016SGC....24..486I |s2cid=131891128|issn=0869-5938}} 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.{{Cite journal|vauthors=Averianov AO, Martin T, Skutschas PP, Danilov IG, Schultz JA, Schellhorn R, et al.|date=2016|title=Middle Jurassic vertebrate assemblage of Berezovsk coal mine in western Siberia (Russia)|journal=Global Geology|volume=19|issue=4|pages=187–204|doi=10.3969/j.issn.1673-9736.2016.04.01}} 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.{{Cite journal|title=THE ILANSK FORMATION AND ITS STRATOȚYPE|journal=Russian Geology and Geophysics}} 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{{Cite journal|last1=Le Heron|first1=Daniel Paul|last2=Buslov|first2=Micha M.|last3=Davies|first3=Clare|last4=Richards|first4=Keith|last5=Safonova|first5=Inna|date=July 2008|title=Evolution of Mesozoic fluvial systems along the SE flank of the West Siberian Basin, Russia|url=https://linkinghub.elsevier.com/retrieve/pii/S0037073808001085|journal=Sedimentary Geology|language=en|volume=208|issue=1–2|pages=45–60|doi=10.1016/j.sedgeo.2008.05.001|bibcode=2008SedG..208...45L }}
Locality
Most of the fossils were found in the overburden of Berezovsk coal mine[
Paleobiota
= Fish =
class="wikitable" align="center" width="100%"
! colspan="7" align="center" |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 =
= Turtles =
class="wikitable" align="center" width="100%"
! colspan="7" align="center" |Turtles of the Itat Formation |
Genus
!Species !Location !Stratigraphic position !Abundance !Notes !Images |
---|
Annemys
|Berezovsk coal mine |Upper Member |Thousands of isolated bones and several fragmented specimens, including three partial braincases and larger fragments of connected shell parts{{Cite journal |last1=Danilov |first1=I. G. |last2=Obraztsova |first2=E. M. |last3=Boitsova |first3=E. A. |last4=Skutschas |first4=P. P. |date=March 2018 |title=Diversity of Middle Jurassic Turtles from the Berezovsk Quarry Locality, Krasnoyarsk Region, Russia: Morphology and Histological Study |journal=Paleontological Journal |volume=52 |issue=2 |pages=188–200 |doi=10.1134/s0031030118010070 |issn=0031-0301 |s2cid=90021437}} | |
Testudines
|Indeterminate |Berezovsk coal mine |Upper Member | |Likely one or two taxa distinct from Annemys. | |
= Lepidosauromorphs =
class="wikitable" align="center" width="100%"
! colspan="7" align="center" |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 =
class="wikitable" align="center" width="100%"
! colspan="7" align="center" |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 =
class="wikitable" align="center" width="100%"
! colspan="7" align="center" |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 =
class="wikitable" align="center" width="100%"
! colspan="7" align="center" |Crocodyliforms of the Itat Formation |
Genus
!Species !Location !Stratigraphic position !Abundance !Notes !Images |
---|
Goniopholididae{{Cite journal|last1=Kuzmin|first1=I.T.|last2=Skutschas|first2=P.P.|last3=Grigorieva|first3=O.I.|last4=Krasnolutskii|first4=S.A.|date=2013|title=Goniopholidid crocodylomorph from the Middle Jurassic Berezovsk Quarry locality ( Western Siberia, Russia).|url=https://spbu.pure.elsevier.com/en/publications/goniopholidid-crocodylomorph-from-the-middle-jurassic-berezovsk-q|journal=Proceedings of the Zoological Institute of the Russian Academy of Sciences|volume=317|issue=4|pages=452–458}}
|Indeterminate |Berezovsk coal mine |Upper Member |Several dozens of isolated teeth, osteoderms, and a few cranial fragments | | |
= Dinosaurs =
= Mammaliamorphs =
= Insects =
Numerous insect species are known from the Kubekovo village locality located within the upper member of the formation.{{Cite web|url=https://paleobiodb.org/classic/basicCollectionSearch?collection_no=118010|title=Kubekovo village (PIN collection 1255)|website=Paleobiology Database}}
class="wikitable" align="center" width="100%"
! colspan="7" align="center" |Insects of the Itat Formation |
Genus
!Species !Location !Stratigraphic position !Abundance !Notes !Images |
---|
Epiosmylus
|Epiosmylus longus | | | | rowspan="3" |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 | | | | |
Eoptychoptera
|E. maxima, E. modica, E. paramaculata | | | | rowspan="4" |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 | | | | rowspan="2" |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 | | | | rowspan="3" |Archijassid leafhopper | |
Kisa
|Kisa fasciata | | | | |
Kubecola
|Kubecola guttatus | | | | |
Necrotaulius
|Necrotaulius kubekovi | | | |Necrotauliidae caddisfly | |
Orthophlebia
|Orthophlebia obunca | | | |Orthophlebiidae scorpionfly | |
Flora
class="wikitable" align="center" width="100%"
! colspan="7" align="center" |Flora of the Itat Formation |
Genus
!Species !Location !Stratigraphic position !Abundance !Notes !Images |
---|
Lycopodites
|Indeterminate | | | | |
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 | | | | |
Sphenobaiera
|Indeterminate | | | | |
Stenorachis
|S. cf. scanicus | | | |Gymnosperm | |
Czekanowskia
|Indeterminate | | | | |