The Tiourarén Formation is a geological

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 secondary ...

in the

Agadez Region Agadez Region is one of the seven regions of Niger. At , it covers more than half of Niger's land area, and is the largest region in the country, as well as the largest African state subdivision. The capital of the department is Agadez. Histo ...

of Niger whose strata were originally thought to be

Early Cretaceous The Early Cretaceous (geochronological name) or the Lower Cretaceous ( chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma. Geology Pr ...

. However, re-interpretation of the sediments showed that they are probably

Middle Jurassic The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from about 174.1 to 163.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relatively rare, but geological formations ...

(

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. St ...

) in age.Rauhut and Lopez-Arbarello (2009). "Considerations on the age of the Tiouaren Formation (

Iullemmeden Basin The Iullemmeden Basin (Berber language: Iwellemmedden) is a major sub-Saharan inland basin in West Africa, extending about north to south and east to west. It covers western Niger and parts of Algeria, Mali and Nigeria. It is named after the Iu ...

, Niger, Africa): Implications for Gondwanan Mesozoic terrestrial vertebrate faunas." ''Palaeogeography, Palaeoclimatology, Palaeoecology'', 271: 259-267.Tuiguidit foreland
at

Fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database, a large relational database assembled by hundreds of paleontologists from around the world. History Fossilworks was cre ...

.org It is the uppermost unit of the

Irhazer Group The Irhazer Shale (french: Argiles de l'Irhazer) or Irhazer II Formation is a Middle Jurassic geologic formation of the Irhazer Group in the Agadez Region of Niger. Fossil ornithopod tracks have been reported from the formation.Weishampel, et a ...

. Dinosaur remains are among the fossils that have been recovered from the formation.Weishampel, David B; et al. (2004). "Dinosaur distribution (Early Cretaceous, Africa)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 571-573. .

Description

The formation comprises reddish, almost solid mudstones, which also shows grey and white streaks, probably caused by alternating oxidative and reducing environments. The

depositional environment In geology, depositional environment or sedimentary environment describes the combination of physical, chemical, and biological processes associated with the deposition of a particular type of sediment and, therefore, the rock types that will b ...

has been interpreted as swampy with seasonal flooding in

braided river A braided river, or braided channel, consists of a network of river channels separated by small, often temporary, islands called braid bars or, in English usage, '' aits'' or ''eyots''. Braided streams tend to occur in rivers with high sedime ...

systems.

Fossil content

References

* A. F. d. Lapparent. 1960. Les Dinosauriens du "Continental intercalaire" du Saharal central he dinosaurs of the "Continental Intercalaire" of the central Sahara Mémoires de la Société géologique de France, nouvelle série 39(88A):1-57 * P. C. Sereno, A. L. Beck, D. B. Dutheil, H. C. E. Larsson, G. H. Lyon, B. Moussa, R. W. Sadleir, C. A. Sidor, D. J. Varricchio, G. P. Wilson, and J. A. Wilson. 1999. Cretaceous sauropods from the Sahara and the uneven rate of skeletal evolution among dinosaurs. Science 286:1342-1347 * P. C. Sereno, J. A. Wilson, H. C. E. Larsson, D. B. Dutheil, and H.-D. Sues. 1994. Early Cretaceous dinosaurs from the Sahara. Science 266(5183):267-271 * F. Witzmann, O. Hampe, B. M. Rothschild, U. Joger, R. Kosma, D. Schwarz, and P. Asbach. 2016. Subchondral cysts at synovial vertebral joints as analogies of Schmorl's Nodes in a sauropod dinosaur from Niger. Journal of Vertebrate Paleontology 36(2):e1080719:1-11 {{DEFAULTSORT:Tiouraren Formation Geologic formations of Niger Mesozoic Niger Jurassic System of Africa Middle Jurassic Africa Bathonian Stage Oxfordian Stage Siltstone formations Mudstone formations Fluvial deposits Paludal deposits Paleontology in Niger Formations

Description

Fossil content

See also

References

Further reading