Jaisalmer Formation | |
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Stratigraphic range: Middle-Late Jurassic, | |
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 |
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]
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]
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]
Sauropods of the Jaisalmer Formation | |||||
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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 | |||||
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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 | |||||
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Genus | Species | Locality | Material | Notes | Photos |
Crocodylomorpha | Indeterminate | Scutes. | |||
Neodiapsida | Indeterminate | Teeth. | Either a sauropterygian, thalattosaurian, choristodere or an ichthyosauromorph. |
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. |