Jaisalmer Formation

Short description: Geologic formation in India

Jaisalmer Formation
Stratigraphic range: Middle-Late Jurassic, Bajocian–Oxfordian

PreЄ

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]

## Contents

* 1 Sub-units
* 2 Paleofauna
* 2.1 Ichnofossils
* 2.2 Sharks
* 2.3 Dinosaurs
* 3 References

## Sub-units

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.[4] The Badabag Member consists of intraformational conglomerate and is fossil bearing.[5]

## Paleofauna

### Ichnofossils

* (?)Bichordites sp. – "Ichnofossils"[6]
* Cytherella indica[7]
* Micropneumatocythere joyanensis[7]
* Planolites .sp – "Ichnofossils"[6]
* Progonocythere khoslai[7]
* Rhizocorallium irregulare – "Ichnofossils"[6]
* Rhizocorallium jenense – "Ichnofossils"[6]
* Taenidium serpentinum – "Ichnofossils"[6]
* Thalassinoides .sp – "Ichnofossils"[6]
* Trichordis minuta[7]

### Sharks

* Strophodus jaisalmerensis
* Strophodus indicus[8]
* Strophodus magnus[8]
* Strophodus medius[8]
* Planohybodus sp.[8]

### Dinosaurs

* Turiasauria indet. – "Fragmentary tooth"[5]
* Averostra indet. - isolated tooth[9]
* Spinosauridae Indet. - "Pedal ungual phalanx"[10]
* Tharosaurus indicus \- a dicraeosaurid sauropod[11]

## References

1. ↑ 1.0 1.1 Oldham, R.D., (1886). Preliminary note on the geology of northern Jaisalmer. Record Geological Survey of India, 19,157-160.
2. ↑ 2.0 2.1 2.2 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. http://dx.doi.org/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. ↑ Narayanan, K., Subrahmanyan, M., Srinivasan, S., (1961). Geology of Jaisalmer. Unpublished report, Oil and Natural Gas Corporation Dehradun, India.
5. ↑ 5.0 5.1 "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 304 (2): 187–203. 2022. doi:10.1127/njgpa/2022/1064.
6. ↑ 6.0 6.1 6.2 6.3 6.4 6.5 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
7. ↑ 7.0 7.1 7.2 7.3 Kumari, M. (2023). "Middle Jurassic Ostracodes from Joyan Member, Jaisalmer Formation, Jaisalmer, Rajasthan, India". Paleontological Journal 57 (7): 775–783. doi:10.1134/S0031030123070055.
8. ↑ 8.0 8.1 8.2 8.3 "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. 2021. doi:10.1127/njgpa/2021/1014.
9. ↑ Sharma, Archana; Hendrickx, Christophe; Singh, Sanjay (2023-01-23). "First Theropod Record from the Marine Bathonian of Jaisalmer Basin, Tethyan Coast of Gondwanan India" (in en). Rivista Italiana di Paleontologia e Stratigrafia 129 (1). doi:10.54103/2039-4942/18306. ISSN 2039-4942. https://riviste.unimi.it/index.php/RIPS/article/view/18306.
10. ↑ 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. https://riviste.unimi.it/index.php/RIPS/article/view/20032.
11. ↑ 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. doi:10.1038/s41598-023-39759-2. PMID 37542094. Bibcode: 2023NatSR..1312680B.

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