Jaisalmer Formation
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]
| Jaisalmer Formation | |
|---|---|
| Stratigraphic range: Middle-Late Jurassic, | |
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 | 26.911661°N 70.922928°E |
| Country | India |
| Extent | Jaisalmer |
| Type section | |
| Named for | Jaisalmer, India |
| Named by | Richard Dixon Oldham |
| Year defined | 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
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
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
Dinosaurs
| Sauropods of the Jaisalmer Formation | |||||
|---|---|---|---|---|---|
| Genus | Species | Locality | Material | Notes | Photos |
| Turiasauria[6] | indeterminate | Fragmentary tooth. | The oldest Turiasaur. | ||
| Tharosaurus[8] | T. indicus | Partial cervical, dorsal, and caudal vertebrae and a dorsal rib. | Oldest Dicraeosaurid and oldest Diplodocoid. |
| |
| Theropods of the Jaisalmer Formation | |||||
|---|---|---|---|---|---|
| Genus | Species | Locality | Material | Notes | Photos |
| Spinosauridae[9] | Indeterminate | Pedal ungual phalanx. | Possibly the oldest spinosaurid. Had affinities with spinosaurinae. | ||
| Averostra[10] | indeterminate | Isolated tooth. | A possible Ceratosaur or a Non Spinosaurid Megalosauroid or a Allosauroid. | ||
Other Reptiles
| Reptiles of the Jaisalmer Formation | |||||
|---|---|---|---|---|---|
| Genus | Species | Locality | Material | Notes | Photos |
| Crocodylomorpha | Indeterminate | Scutes. | |||
| Neodiapsida | Indeterminate | Teeth. | Either a sauropterygian, thalattosaurian, choristodere or an ichthyosauromorph. | ||
Fish
| Sharks of the Jaisalmer Formation | |||||
|---|---|---|---|---|---|
| Genus | Species | Locality | Material | Notes | Photos |
| Strophodus | S. jaisalmerensis | Teeth. | Hybodont shark. | ||
| S. indicus[11] | Teeth. | Hybodont shark. | |||
| S. magnus[11] | Teeth. | Hybodont shark. | |||
| S. medius[11] | Teeth. | Hybodont shark. | |||
| Planohybodus | P. sp. [11] | Teeth. | Hybodont shark. | ||
| Osteichthyes[10] | Indeterminate. | Teeth and scales. | Found along with an averostran tooth. | ||
| cf. Eomesodon[12] | cf. Eomesodon sp. | Prearticular dental plate and isolated teeth. | Oldest East Gondwanan Pycnodont. | ||
Ichnofossils
- (?)Bichordites sp. – "Ichnofossils"[13]
- Cytherella indica[14]
- Micropneumatocythere joyanensis[14]
- Planolites .sp – "Ichnofossils"[13]
- Progonocythere khoslai[14]
- Rhizocorallium irregulare – "Ichnofossils"[13]
- Rhizocorallium jenense – "Ichnofossils"[13]
- Taenidium serpentinum – "Ichnofossils"[13]
- Thalassinoides .sp – "Ichnofossils"[13]
- Trichordis minuta[14]
References
- Oldham, R.D., (1886). Preliminary note on the geology of northern Jaisalmer. Record Geological Survey of India, 19,157-160.
- 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.
- 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.
- 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) - Narayanan, K., Subrahmanyan, M., Srinivasan, S., (1961). Geology of Jaisalmer. Unpublished report, Oil and Natural Gas Corporation Dehradun, India.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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
- Kumari, M. (2023). "Middle Jurassic Ostracodes from Joyan Member, Jaisalmer Formation, Jaisalmer, Rajasthan, India". Paleontological Journal. 57 (7): 775–783. doi:10.1134/S0031030123070055.
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