| Jaisalmer Formation | |
| Country: |  India |
| Thickness: | Variable, typically 120km-170kmkm (80miles-110mileskm) |
| Overlies: | Lathi Formation |
| Underlies: | Baisakhi Formation |
| Subunits: | Badabag Member, Fort Member, Hamira Member, Jajiya Member, Joyan Member, Kuldhar Member |
| Namedby: | Richard Dixon Oldham |
| Namedfor: | Jaisalmer, India |
| Otherlithology: | Limestone |
| Prilithology: | Siltstone, sandstone |
| Period: | Middle Jurassic |
| Age: | Middle-Late Jurassic, |
| Type: | Geological formation |
| Extent: | Jaisalmer |
| Year Ts: | 1886[1] |
| Coordinates: | 26.9117°N 70.9229°W |
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.
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]
The Badabag, Fort, Joyan and Hamira members represent the Middle Jurassic Bajocian and Bathonian stages, while the Jajiya and Kuldhar members represent the Middle Jurassic Callovian and the Late Jurassic Oxfordian stages.
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.
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. The Kuldhar Member Limestone contained carbonate microfacies that also indicate a depositional environment composed mainly of lagoons, shoals and open marine environments.[6]
| Sauropods of the Jaisalmer Formation | |||||
|---|---|---|---|---|---|
| Genus | Species | Locality | Material | Notes | Photos |
| Turiasauria[7] | 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. | ||
| 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. | ||
| Fishes of the Jaisalmer Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Locality | Material | Notes | Photos | |
| Strophodus | S. jaisalmerensis | Teeth. | A Hybodont shark. | |||
| S. indicus[11] | ||||||
| S. magnus | ||||||
| S. medius | ||||||
| Planohybodus | P. sp. | Teeth. | A Hybodont shark. | |||
| Osteichthyes | 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. | |||