The Jaisalmer Formation is a Middle to

Late Jurassic The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987. In European lithostratigraphy, the name ...

-aged geologic

formation Formation may refer to: Linguistics * Back-formation, the process of creating a new lexeme by removing or affixes * Word formation, the creation of a new word by adding affixes Mathematics and science * Cave formation or speleothem, a secondar ...

located in

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

near the city of

Jaisalmer Jaisalmer , nicknamed "The Golden city", is a city in the Indian state of Rajasthan, located west of the state capital Jaipur. The town stands on a ridge of yellowish sandstone and is crowned by the ancient Jaisalmer Fort. This fort contains a ...

that consists mainly of marine deposits. The formation was first identified and defined by

geologist A geologist is a scientist who studies the solid, liquid, and gaseous matter that constitutes Earth and other terrestrial planets, as well as the processes that shape them. Geologists usually study geology, earth science, or geophysics, althoug ...

Richard Dixon Oldham in 1886.

Dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

remains are among the known fossils recovered from this formation.Weishampel, David B; et al. (2004). "Dinosaur distribution (Late Cretaceous, Asia)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): ''

The Dinosauria ''The Dinosauria'' is an extensive book on dinosaurs, compiled by David B. Weishampel, Peter Dodson, and Halszka Osmólska. It has been published in 2 editions, with the first edition published in 1990, consisting of material from 23 scientists.B ...

'', 2nd, ''Berkeley: University of California Press''. Pp. 593–600. .

Sub-units

The Badabag, Fort, Joyan and Hamira members represent the Middle Jurassic

Bajocian In the geologic timescale, the Bajocian is an age and stage in the Middle Jurassic. It lasted from approximately 170.3 Ma to around 168.3 Ma (million years ago). The Bajocian Age succeeds the Aalenian Age and precedes the Bathonian Age. Stra ...

and

Bathonian In the geologic timescale the Bathonian is an age and stage of the Middle Jurassic. It lasted from approximately 168.3 Ma to around 166.1 Ma (million years ago). The Bathonian Age succeeds the Bajocian Age and precedes the Callovian Age. Str ...

stages, while the Jajiya and Kuldhar members represent the Middle Jurassic Callovian and the

Oxfordian stages. The Fort Member is the most extensively studied and consists of fine to medium grain sandstones and oolitic limestones. The Badabag Member consists of intraformational conglomerate and is fossil bearing.

Paleofauna

* (?)'' Bichordites'' sp. – "Ichnofossils"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 * '' Planolites'' .sp – "Ichnofossils" * '' Rhizocorallium irregulare'' – "Ichnofossils" * '' Rhizocorallium jenense'' – "Ichnofossils" * '' Taenidium serpentinum'' – "Ichnofossils" * ''

Thalassinoides ''Thalassinoides'' is an ichnogenus of trace fossil used to refer to "dichotomously or T-branched boxworks, mazes and shafts, unlined and unornamented". Facies of ''Thalassinoides'' increased suddenly in abundance at the beginning of the Mesozoic ...

'' .sp – "Ichnofossils" * aff.

Turiasauria Turiasauria is an unranked clade of basal sauropod dinosaurs known from Middle Jurassic to Early Cretaceous deposits in Europe, North America, and Africa. Description Turiasauria was originally erected by Royo-Torres et al. (2006) to include '' ...

indet. – "Fragmentary tooth" *

Averostra Averostra, or "bird snouts", is a clade that includes most theropod dinosaurs, namely Ceratosauria and Tetanurae, and represent the only group of post-Early Jurassic theropods. Both survived into the Cretaceous period. When the Cretaceous–Pa ...

indet. - isolated tooth * ''

Strophodus ''Strophodus'' is an extinct genus of hybodonts known from the Triassic to Cretaceous. It has heavily rounded, durophagous teeth. It has long been confused with ''Asteracanthus'' due to the fin spines of the latter being found associated with the ...

jaisalmerensis'' * ''

indicus''

References

{{reflist Geologic groups of Asia Geologic formations of India Oxfordian Stage Callovian Stage Bathonian Stage Bajocian Stage Paleontology in India