Jaisalmer Formation | |
---|---|
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″N70°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 comprised mainly of lagoons, shoals and open marine environments. [7]
This section needs expansion. You can help by adding to it. (August 2022) |
Dinosaurs of the Jaisalmer Formation | ||||
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Genus | Species | Material | Notes | Photos |
Turiasauria indet. [6] | Fragmentary tooth | Possibly the oldest Turiasaur | ||
Averostra indet. [8] | isolated tooth | A possible Ceratosaur or a Non Spinosaurid Megalosauroid | ||
Spinosauridae Indet. [9] | Pedal ungual phalanx | Possibly the oldest Spinosaurid | ||
Tharosaurus [10] | T. indicus | Partial cervical, dorsal, and caudal vertebrae and a dorsal rib | Oldest Dicraeosaurid and oldest Diplodocoid | |
Reptiles of the Jaisalmer Formation | ||||
---|---|---|---|---|
Genus | Species | Material | Notes | Photos |
Crocodylomorpha | Indeterminate | Scutes | ||
Diapsida | Indeterminate | Teeth | Either a Sauropterygia, Thalattosauria, Choristodera or an Ichthyosauromorpha | |
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