Jaisalmer Formation

Geologic formation in India

Jaisalmer Formation

Stratigraphic range: Middle-Late Jurassic, Bajocian–Oxfordian

PreꞒ

An outcrop of the Jaisalmer Formation which is the type locality for Tharosaurus indicus. Photographed between 2019-21.

Type| Geological formation
Sub-units| Badabag Member, Fort Member, Hamira Member, Jajiya Member, Joyan Member, Kuldhar Member
Underlies| Baisakhi Formation
Overlies| Lathi Formation
Thickness| Variable, typically 120–170 km (75–106 mi)
Lithology
Primary| Siltstone, sandstone
Other| Limestone
Location
Coordinates| 26°54′42″N 70°55′23″E﻿ / ﻿26.911661°N 70.922928°E﻿ / 26.911661; 70.922928
Country| India
Extent| Jaisalmer
Type section
Named for| Jaisalmer, India
Named by| Richard Dixon Oldham
Year defined| 1886[1]

The Jaisalmer Formation is a Middle to Late Jurassic-aged geologic formation located in India near the city of Jaisalmer that consists mainly of marine deposits.[2] The formation was first identified and defined by geologist Richard Dixon Oldham in 1886.[1]

Dinosaur remains are among the known fossils recovered from this formation.[3]

Strophodus jaisalmerensis, a hybodont, was named after this formation and the Jaisalmer District where its holotype was found.[4]

## Sub-units

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The Badabag, Fort, Joyan and Hamira members represent the Middle Jurassic Bajocian and Bathonian stages,[2] while the Jajiya and Kuldhar members represent the Middle Jurassic Callovian and the Late Jurassic Oxfordian stages.[2]

The Fort Member is the most extensively studied and consists of fine to medium grain sandstones and oolitic limestones.[5] The Badabag Member consists of intraformational conglomerate and is fossil bearing.[6]

## Paleoenvironment

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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 Tethyan coast of Gondwanan India. A marine paleoenvironment is supported by the presence of Hybodont sharks.[4] The Kuldhar Member Limestone contained carbonate microfacies that also indicate a depositional environment composed mainly of lagoons, shoals and open marine environments.[7]

## Paleofauna

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This section needs expansion. You can help by adding to it. (August 2022)

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Color key
| Taxon | Reclassified taxon | Taxon falsely reported as present | Dubious taxon or junior synonym | Ichnotaxon | Ootaxon | Morphotaxon

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| Notes
Uncertain or tentative taxa are in small text; ~~crossed out~~ taxa are discredited.

### Dinosaurs

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#### Sauropods

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Sauropods of the Jaisalmer Formation

Genus | Species | Locality | Material | Notes | Photos
Turiasauria[6] | indeterminate  | Chandoo Village quarry  | Fragmentary tooth.  | The oldest turiasaur.  |
Tharosaurus[8] | T. indicus | Jethwai Village  | Partial cervical, dorsal, and caudal vertebrae and a dorsal rib.  | Oldest dicraeosaurid and oldest diplodocoid.  |

#### Theropods

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Theropods of the Jaisalmer Formation

Genus | Species | Locality | Material | Notes | Photos
Spinosauridae[9] | Indeterminate  | Chandoo Village quarry  | Pedal ungual phalanx.  | Possibly the oldest spinosaurid. Had affinities with spinosaurinae.  | Specimen RAJ/JAIS/CVQS002
Averostra[10] | indeterminate  | Chandoo Village quarry  | Isolated tooth.  | A possible Ceratosaur or a Non Spinosaurid Megalosauroid or a Allosauroid.  |

### Other Reptiles

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Reptiles of the Jaisalmer Formation

Genus | Species | Locality | Material | Notes | Photos
Crocodylomorpha[6] | Indeterminate  | Chandoo Village quarry  | Scutes.  |  |
Neodiapsida[6][10] | Indeterminate  | Chandoo Village quarry  | Teeth.  | Either a sauropterygian, thalattosaurian, choristodere or an ichthyosauromorph.  |

### Fish

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Fishes of the Jaisalmer Formation

Genus | Species | Locality | Material | Notes | Photos
Hybodontiformes Indet.[11] | Indeterminate  |  |  |  |
Strophodus | S. jaisalmerensis | Jethwai village  | Teeth.  | A hybodont shark.  |
S. indicus[12] | Chandoo Village quarry
S. magnus[12] | Chandoo Village quarry
S. medius[12] | Chandoo Village quarry
Planohybodus | P. aff. grossiconus [12] | Chandoo Village quarry  | Teeth.  | A hybodont shark.  |
Osteichthyes[10] | Indeterminate.  | Chandoo Village quarry  | Teeth and scales.  | Found along with an averostran tooth.  |
cf. Eomesodon[13] | cf. Eomesodon sp. | Jethwai Village  | Prearticular dental plate and isolated teeth.  | Oldest East Gondwanan Pycnodont.  |

### Crustaceans

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Crustaceans of the Jaisalmer Formation

Genus | Species | Locality | Material | Notes | Photos
Cytherella[14] | C. indica |  |  |  |
Micropneumatocythere[14] | M. joyanensis |  |  |  |
Progonocythere[14] | P. khoslai |  |  |  |
Trichordis[14] | T. minuta |  |  |  |

### Ichnofossils

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* (?)Bichordites sp. – "Ichnofossils"[15]
* Planolites .sp – "Ichnofossils"[15]
* Rhizocorallium irregulare – "Ichnofossils"[15]
* Rhizocorallium jenense – "Ichnofossils"[15]
* Taenidium serpentinum – "Ichnofossils"[15]
* Thalassinoides .sp – "Ichnofossils"[15]

## References

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1. ^ a b Oldham, R.D., (1886). Preliminary note on the geology of northern Jaisalmer. Record Geological Survey of India, 19,157-160.
2. ^ a b c Ahmad, Faiz; Quasim, Mohammad Adnan; Ahmad, Abul Hasnat Masood (January 2021). "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". Geological Journal. 56 (1): 130–151\. doi:10.1002/gj.3945/v1/review2.
3. ^ 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.
4. ^ a b Krishna Kumara, Sunil Bajpaib, Pragya Pandeya, Triparna Ghosha, Debasish Bhattacharya (2021). "Hybodont sharks from the Jurassic of Jaisalmer, western India". Historical Biology. 34 (6): 953-963. doi:10.1080/08912963.2021.1954920.`{{cite journal}}`: CS1 maint: multiple names: authors list (link)
5. ^ Narayanan, K., Subrahmanyan, M., Srinivasan, S., (1961). Geology of Jaisalmer. Unpublished report, Oil and Natural Gas Corporation Dehradun, India.
6. ^ a b c d Sharma, Archana; Singh, Sanjay; S. R., Satheesh (2022-06-10). "The first turiasaurian sauropod of India reported from the Middle Jurassic (Bathonian) sediments of Jaisalmer Basin, Rajasthan, India". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen: 187–203\. doi:10.1127/njgpa/2022/1064.
7. ^ Asjad, Shaikh; Khan, K. F.; Quasim, M. A.; Sachan, H. K.; Javed, Aashna (2023-11-06). "Microfacies and stable isotope analysis of Kuldhar Member Limestone (Callovian–Oxfordian), Jaisalmer Basin, western Rajasthan: implications for depositional environment and diagenetic evolution". Carbonates and Evaporites. 38 (4): 81. doi:10.1007/s13146-023-00905-6. ISSN 1878-5212.
8. ^ Bajpai, S.; Datta, D.; Pandey, P.; Ghosh, T.; Kumar, K.; Bhattacharya, D. (2023). "Fossils of the oldest diplodocoid dinosaur suggest India was a major centre for neosauropod radiation". Scientific Reports. 13 (1). 12680. Bibcode:2023NatSR..1312680B. doi:10.1038/s41598-023-39759-2. PMC 10403599. PMID 37542094.
9. ^ Sharma, A.; Novas, F. E.; Singh, S. (2023). "First Jurassic evidence of a possible spinosaurid pedal ungual from the Jaisalmer Basin, India". Rivista Italiana di Paleontologia e Stratigrafia. 129 (3): 653–670\. doi:10.54103/2039-4942/20032.
10. ^ a b c Sharma, Archana; Hendrickx, Christophe; Singh, Sanjay (2023-01-23). "First Theropod Record from the Marine Bathonian of Jaisalmer Basin, Tethyan Coast of Gondwanan India". Rivista Italiana di Paleontologia e Stratigrafia. 129 (1). doi:10.54103/2039-4942/18306. ISSN 2039-4942. S2CID 256347914.
11. ^ Ghosh, T.; Swami, N. K.; Kumar, K.; Maurya, A. S.; Bajpai, S. (2024). "An assemblage of Middle Jurassic hybodonts from Jaisalmer Basin, western India". Historical Biology: An International Journal of Paleobiology. doi:10.1080/08912963.2024.2412131.
12. ^ a b c d Sharma A, Singh S (2021). "A small assemblage of marine hybodont sharks from the Bathonian of the Jaisalmer Basin, India". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen. 301 (3): 317–333\. doi:10.1127/njgpa/2021/1014. S2CID 239669413.
13. ^ Kumar, Krishna; Bajpai, Sunil; Ghosh, Triparna; Pandey, Pragya; Bhattacharya, Debasish (2022-12-01). "Oldest East Gondwanan pycnodont fishes (Neopterygii, Pycnodontiformes) from the Middle Jurassic (Bathonian) of Jaisalmer, western India". PalZ. 96 (4): 795–804\. doi:10.1007/s12542-022-00619-5. ISSN 1867-6812.
14. ^ a b c d Kumari, M. (2023). "Middle Jurassic Ostracodes from Joyan Member, Jaisalmer Formation, Jaisalmer, Rajasthan, India". Paleontological Journal. 57 (7): 775–783\. doi:10.1134/S0031030123070055.
15. ^ a b c d e f 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