DenaDelamothe53 at 19:47, 21 December 2025

2025-12-21T19:47:55Z

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{{Short description|Geologic formation in India}}
{{Infobox Rockunit
|name=Jaisalmer Formation
|country=[[India]]
|thickness=Variable, typically {{convert|120|-|170|km|abbr=on}}
|image = File:Jaisalmer_Formation_Tharosaurus_type_locality.png
|imagesize = 250px
|caption = An outcrop of the Jaisalmer Formation which is the type locality for ''[[Tharosaurus indicus]]''. Photographed between 2019-21.
|overlies=[[Lathi Formation]]
|underlies=[[Baisakhi Formation]]
|subunits=Badabag Member, Fort Member, Hamira Member, Jajiya Member, Joyan Member, Kuldhar Member
|unitof=
|paleocoordinates=
|region=
|namedby=[[Richard Dixon Oldham]]
|namedfor=[[Jaisalmer]], India
|otherlithology=[[Limestone]]
|prilithology=[[Siltstone]], [[sandstone]]
|period=Middle Jurassic
|age=[[Middle Jurassic|Middle]]-[[Late Jurassic]], {{fossilrange|Bajocian|Oxfordian}}
|type=[[Geological formation]]
|extent=Jaisalmer
|year_ts=1886<ref name=Oldham86>Oldham, R.D., (1886). Preliminary note on the geology of northern
Jaisalmer. ''Record Geological Survey of India'', 19,157-160.</ref>
|coordinates={{coord|26.911661|N|70.922928|E|display=inline,title}}
}}

The '''Jaisalmer Formation''' is a [[Middle Jurassic|Middle]] to [[Late Jurassic]]-aged [[Geological formation|geologic formation]] located in [[India]] near the city of [[Jaisalmer]] that consists mainly of marine deposits.<ref name="Jaisalmur">{{Cite journal |last1=Ahmad |first1=Faiz |last2=Quasim |first2=Mohammad Adnan |last3=Ahmad |first3=Abul Hasnat Masood |title=Review for "Microfacies and diagenetic overprints in the limestones of Middle Jurassic Fort Member (Jaisalmer Formation), Western Rajasthan, India: Implications for the depositional environment, cyclicity, and reservoir quality |journal=Geological Journal |volume=56 |issue=1 |pages=130–151 |date=January 2021 |url=http://dx.doi.org/10.1002/gj.3945/v1/review2 |doi=10.1002/gj.3945/v1/review2|url-access=subscription |doi-access=free }}</ref> The formation was first identified and defined by [[geologist]] [[Richard Dixon Oldham]] in 1886.<ref name="Oldham86" />

[[Dinosaur]] remains are among the known [[Fossil|fossils]] recovered from this formation.<ref name="Weishampel-2004">Weishampel, David B; et al. (2004). "Dinosaur distribution (Late Cretaceous, Asia)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): ''[[The Dinosauria]]'', 2nd, ''Berkeley: University of California Press''. Pp. 593–600. {{ISBN|0-520-24209-2}}.</ref>

''[[Strophodus|Strophodus jaisalmerensis]]'', a [[hybodont]], was named after this formation and the [[Jaisalmer District]] where its [[holotype]] was found.<ref name=":0">{{cite journal|year=2021|author=Krishna Kumara, Sunil Bajpaib, Pragya Pandeya, Triparna Ghosha, Debasish Bhattacharya|title=Hybodont sharks from the Jurassic of Jaisalmer, western India|journal=Historical Biology|volume=34|issue=6|page=953-963|doi=10.1080/08912963.2021.1954920}}</ref>

== Sub-units ==
The Badabag, Fort, Joyan and Hamira members represent the [[Middle Jurassic]] [[Bajocian]] and [[Bathonian]] stages,<ref name="Jaisalmur" /> while the Jajiya and Kuldhar members represent the Middle Jurassic Callovian and the [[Late Jurassic]] [[Oxfordian (stage)|Oxfordian]] stages.<ref name="Jaisalmur" />

The Fort Member is the most extensively studied and consists of fine to medium grain sandstones and oolitic limestones.<ref>Narayanan, K., Subrahmanyan, M., Srinivasan, S., (1961). Geology of Jaisalmer. Unpublished report, Oil and Natural Gas Corporation Dehradun, India.</ref> The Badabag Member consists of [[Conglomerate (geology)|intraformational conglomerate]] and is fossil bearing.<ref name=":1" />

== Paleoenvironment ==
The Jaisalmer district of India is a landlocked district in the state of [[Rajasthan]]. However, during the Middle Jurassic, the Jaisalmer Formation was located on the [[Tethys Ocean|Tethyan]] coast of [[Gondwanan]] India. A marine paleoenvironment is supported by the presence of Hybodont sharks.<ref name=":0" /> The Kuldhar Member Limestone contained carbonate microfacies that also indicate a depositional environment composed mainly of [[Lagoon|lagoons]], [[Shoal|shoals]] and [[Ocean|open marine environments]].<ref>{{Cite journal |last=Asjad |first=Shaikh |last2=Khan |first2=K. F. |last3=Quasim |first3=M. A. |last4=Sachan |first4=H. K. |last5=Javed |first5=Aashna |date=2023-11-06 |title=Microfacies and stable isotope analysis of Kuldhar Member Limestone (Callovian–Oxfordian), Jaisalmer Basin, western Rajasthan: implications for depositional environment and diagenetic evolution |url=https://doi.org/10.1007/s13146-023-00905-6 |journal=Carbonates and Evaporites |language=en |volume=38 |issue=4 |pages=81 |doi=10.1007/s13146-023-00905-6 |issn=1878-5212|url-access=subscription }}</ref>

== Paleofauna ==
{{expand_section|date=August 2022}}
{{paleobiota-key-compact}}
===Dinosaurs===

==== Sauropods ====
{| class="wikitable" align="center"
|-
! colspan="6" align="center" | [[Sauropoda|Sauropods]] of the Jaisalmer Formation
|-
! Genus !! Species !! Locality!! Material !! Notes !! Photos
|-
|[[Turiasauria]] indet.<ref name=":1">{{Cite journal |last=Sharma |first=Archana |last2=Singh |first2=Sanjay |last3=S. R. |first3=Satheesh |date=2022-06-10 |title=The first turiasaurian sauropod of India reported from the Middle Jurassic (Bathonian) sediments of Jaisalmer Basin, Rajasthan, India |url=https://www.schweizerbart.de/papers/njgpa/detail/304/101378/The_first_turiasaurian_sauropod_of_India_reported_from_the_Middle_Jurassic_Bathonian_sediments_of_Jaisalmer_Basin_Rajasthan_India |journal=Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen |language=en |pages=187–203 |doi=10.1127/njgpa/2022/1064|url-access=subscription }}</ref>
| Indeterminate
|Chandoo Village quarry
| Fragmentary tooth
| A turiasaur
|
|-
| ''[[Tharosaurus]]''<ref name="Tharosaurus"> {{Cite journal |last1=Bajpai |first1=S. |last2=Datta |first2=D. |last3=Pandey |first3=P. |last4=Ghosh |first4=T. |last5=Kumar |first5=K. |last6=Bhattacharya |first6=D. |year=2023 |title=Fossils of the oldest diplodocoid dinosaur suggest India was a major centre for neosauropod radiation |journal=Scientific Reports |volume=13 |issue=1 |at=12680 |doi=10.1038/s41598-023-39759-2 |pmid=37542094 |pmc=10403599 |bibcode=2023NatSR..1312680B |doi-access=free }}</ref>
| ''T. indicus''
|Jethwai Village
| Partial cervical, dorsal, and caudal vertebrae and a dorsal rib
| A potentially [[Nomen dubium|dubious]] [[eusauropod]]
|
[[File:Tharosaurus (cervical vertebrae).jpg|frameless]]
|-
|}

==== Theropods ====
{| class="wikitable" align="center"
|-
! colspan="6" align="center" | [[Theropoda|Theropods]] of the Jaisalmer Formation
|-
! Genus !! Species !! Locality!! Material !! Notes !! Photos
|-
| [[Spinosauridae]] indet.<ref>{{Cite journal |last1=Sharma |first1=A. |last2=Novas |first2=F. E. |last3=Singh |first3=S. |title=First Jurassic evidence of a possible spinosaurid pedal ungual from the Jaisalmer Basin, India |year=2023 |journal=Rivista Italiana di Paleontologia e Stratigrafia |volume=129 |issue=3 |pages=653–670 |doi=10.54103/2039-4942/20032 |url=https://riviste.unimi.it/index.php/RIPS/article/view/20032 |doi-access=free }}</ref>
|Indeterminate
|Chandoo Village quarry
| Pedal ungual phalanx
| Possibly the oldest [[spinosaurid]]
|[[File:Pedal ungual phalanx from the Bathonian of Jaisalmer Basin, India. Specimen RAJ JAIS CVQS002.png|frameless]]
|-
| [[Averostra]] indet.<ref name=":2">{{Cite journal |last1=Sharma |first1=Archana |last2=Hendrickx |first2=Christophe |last3=Singh |first3=Sanjay |title=First Theropod Record from the Marine Bathonian of Jaisalmer Basin, Tethyan Coast of Gondwanan India |journal=Rivista Italiana di Paleontologia e Stratigrafia |date=2023-01-23 |url=https://riviste.unimi.it/index.php/RIPS/article/view/18306 |language=en |volume=129 |issue=1 |doi=10.54103/2039-4942/18306 |s2cid=256347914 |issn=2039-4942|doi-access=free }}</ref>
| Indeterminate
|Chandoo Village quarry
| Isolated tooth
|A possible [[allosauroid]], [[ceratosaur]], or non-[[spinosaurid]] [[megalosauroid]]
|
|-
|}

=== Other reptiles ===
{| class="wikitable" align="center"
|-
! colspan="6" align="center" | [[Reptile|Reptiles]] of the Jaisalmer Formation
|-
! Genus !! Species !! Locality !! Material !! Notes !! Photos
|-
| [[Crocodylomorpha]] indet.<ref name=":1"/>
| Indeterminate
|Chandoo Village quarry
| Scutes
|
|
|-
| [[Neodiapsida]] indet.<ref name=":1"/><ref name=":2"/>
| Indeterminate
|Chandoo Village quarry
| Teeth
| Either a [[Sauropterygia|sauropterygian]], [[Thalattosauria|thalattosaurian]], [[Choristodera|choristodere]] or an [[Ichthyosauromorpha|ichthyosauromorph]].
|
|}

=== Fish ===
{| class="wikitable" align="center"
|-
! colspan="6" align="center" | [[Fish|Fishes]] of the Jaisalmer Formation
|-
! Genus !! Species !! Locality !! Material !! Notes !! Photos
|-
| [[Hybodontiformes]] indet.<ref>{{Cite journal|last1=Ghosh |first1=T. |last2=Swami |first2=N. K. |last3=Kumar |first3=K. |last4=Maurya |first4=A. S. |last5=Bajpai |first5=S. |year=2024 |title=An assemblage of Middle Jurassic hybodonts from Jaisalmer Basin, western India |journal=Historical Biology: An International Journal of Paleobiology |doi=10.1080/08912963.2024.2412131 }}</ref>
| Indeterminate
|
|
|
|
|-
| rowspan = "4"|''[[Strophodus]]''
| ''S. jaisalmerensis''
|Jethwai village
| rowspan="4" | Teeth
| rowspan="4" | A [[Hybodontiformes|hybodont]] [[shark]].
| rowspan="4" |
|-
|''S. indicus''<ref name=Sharma2021>{{Cite journal |vauthors=Sharma A, Singh S |year=2021 |title= A small assemblage of marine hybodont sharks from the Bathonian of the Jaisalmer Basin, India |journal=Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen |volume=301 |issue=3 |pages=317–333 |doi=10.1127/njgpa/2021/1014 |s2cid=239669413}}</ref>
|Chandoo Village quarry
|-
| ''S. magnus''<ref name=Sharma2021/>
|Chandoo Village quarry
|-
|''S. medius''<ref name=Sharma2021/>
|Chandoo Village quarry
|-
| ''[[Planohybodus]]''
| ''P. aff. grossiconus'' <ref name=Sharma2021/>
|Chandoo Village quarry
|Teeth
|A [[Hybodontiformes|hybodont]] shark.
|
|-
|[[Osteichthyes]] indet.<ref name=":2" />
|Indeterminate
|Chandoo Village quarry
|Teeth and scale
|Found along with an averostran tooth.
|
|-
|''[[Eomesodon]]''<ref>{{Cite journal |last=Kumar |first=Krishna |last2=Bajpai |first2=Sunil |last3=Ghosh |first3=Triparna |last4=Pandey |first4=Pragya |last5=Bhattacharya |first5=Debasish |date=2022-12-01 |title=Oldest East Gondwanan pycnodont fishes (Neopterygii, Pycnodontiformes) from the Middle Jurassic (Bathonian) of Jaisalmer, western India |url=https://doi.org/10.1007/s12542-022-00619-5 |journal=PalZ |language=en |volume=96 |issue=4 |pages=795–804 |doi=10.1007/s12542-022-00619-5 |issn=1867-6812|url-access=subscription }}</ref><ref>{{Cite journal|last1=Ghosh |first1=T. |last2=Kumar |first2=K. |last3=Swami |first3=N. K. |year=2025 |title=Middle Jurassic (Bajocian) pycnodont fishes from the Jaisalmer Basin, western India |journal=Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen |volume=316 |issue=2 |pages=121–130 |doi=10.1127/njgpa/1284 |bibcode=2025NJGPA.316..121G }}</ref>
|''E. sp.''
|Jethwai Village
|Prearticular dental plate and isolated teeth
|Oldest East Gondwanan [[Pycnodontiformes|Pycnodont]].
|
|}

=== Crustaceans ===
{| class="wikitable" align="center"
|-
! colspan="6" align="center" | [[Crustacean]]s of the Jaisalmer Formation
|-
! Genus !! Species !! Locality!! Material !! Notes !! Photos
|-
|''[[Cytherella]]''<ref name=PJ577>{{cite journal|last=Kumari |first=M. |year=2023 |title=Middle Jurassic Ostracodes from Joyan Member, Jaisalmer Formation, Jaisalmer, Rajasthan, India |journal=Paleontological Journal |volume=57 |issue=7 |pages=775–783 |doi=10.1134/S0031030123070055 }}</ref>
|''C. indica''
|
|
|
|
|-
|''[[Micropneumatocythere]]''<ref name=PJ577 />
|''M. joyanensis''
|
|
|
|
|-
|''[[Progonocythere]]''<ref name=PJ577 />
|''P. khoslai''
|
|
|
|
|-
|''[[Trichordis]]''<ref name=PJ577 />
|''T. minuta''
|
|
|
|
|}

=== Ichnofossils ===
* ?''[[Bichordites]]'' sp. – Ichnofossils<ref name=Ichno08>Kulkarni, K.G., Borkar, V.D., Petare, T.J., (2008). Ichnofossils from the Fort Member (Middle Jurassic), Jaisalmer Formation, Rajasthan. ''Journal of the Geological Society of India'', 71, 731-738</ref>
* ''[[Planolites]]'' sp. – Ichnofossils<ref name=Ichno08 />
* ''[[Rhizocorallium|Rhizocorallium irregulare]]'' – Ichnofossils<ref name=Ichno08 />
* ''[[Rhizocorallium|Rhizocorallium jenense]]'' – Ichnofossils<ref name=Ichno08 />
* ''[[Taenidium serpentinum]]'' – Ichnofossils<ref name=Ichno08 />
* ''[[Thalassinoides]]'' sp. – Ichnofossils<ref name=Ichno08 />

== References ==
{{reflist}}

[[Category:Geologic groups of Asia]]
[[Category:Geologic formations of India]]
[[Category:Oxfordian Stage]]
[[Category:Callovian Stage]]
[[Category:Bathonian Stage]]
[[Category:Bajocian Stage]]
[[Category:Paleontology in India]]

Jaisalmer Formation - Revision history

DenaDelamothe53 at 19:47, 21 December 2025