Guichón Formation

Guichón Formation
Guichón Formation
Stratigraphic range: Aptian-Santonian; ~125–85 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Type	Geological formation
Unit of	Paysandú Group
Underlies	Mercedes Formation
Overlies	Arapey Formation
Thickness	Up to >100 m (330 ft) (in wells)
Lithology
Primary	Sandstone
Other	Conglomerate
Location
Coordinates	32°00′S 57°42′W / 32.0°S 57.7°W
Approximate paleocoordinates	38°24′S 30°00′W / 38.4°S 30.0°W
Region	Paysandú Department
Country	Uruguay
Extent	Norte Basin
Type section
Named for	Guichón
	Guichón Formation (Uruguay)

The Guichón Formation is a Late Cretaceous geologic formation of the Paysandú Group in Uruguay. Dinosaur remains are among the fossils that have been recovered from the formation.^[1]

Description[edit]

The Guichón Formation comprises mainly pink-greyish to reddish sandstones, which contain moderate to well-sorted, subrounded, fine to medium-sized grains in a pelitic matrix. These sandstones (which compositionally are feldspathic wackes) are either massive or may instead exhibit parallel lamination, cross-lamination and graded bedding. These lithologies were deposited in southwest-trending alluvial–fluvial systems comprising low-sinuosity channels traversing through sandy plains. Subordinate to the already mentioned sandstones are conglomeratic and pelitic lithologies, interpreted as channel-fill and overbank deposits, respectively. It is inferred that the Guichón Formation was deposited in warm, semi-arid climatic conditions.^[2] The formation has been correlated to the Puerto Yeruá Formation of northwestern Argentina.^[3]

The formation reaches a thickness of more than 100 metres (330 ft) in wells perforating the formation.^[4] It is overlain by the Mercedes Formation and overlies the Arapey Formation.^[5]

Fossil content[edit]

The following fossils have been reported from the formation:^[2]^[6]

Fossil eggs

Sphaerovum sp.^[10]

References[edit]

^ Weishampel et al., 2004, pp.517-607
^ ^a ^b Guichón at Fossilworks.org
^ Soto et al., 2009, p.13
^ Tofalo et al., 2011, p.616
^ Tofalo et al., 2011, p.617
^ Soto et al., 2009, p.19
^ Soto, M.; Carballido, J. L.; Langer, M. C.; Silva Junior, J. C. G.; Montenegro, F.; Perea, D. (2024). "Phylogenetic relationships of a new titanosaur (Dinosauria, Sauropoda) from the Upper Cretaceous of Uruguay". Cretaceous Research. 105894. doi:10.1016/j.cretres.2024.105894.
^ Mones, 1972
^ ^a ^b Soto et al., 2011
^ Soto et al., 2012

Bibliography[edit]

Soto, M.; D. Perea, and A. Cambiaso. 2012. First sauropod (Dinosauria: Saurischia) remains from the Guichón Formation, Late Cretaceous of Uruguay. Journal of South American Earth Sciences 33. 68–79. .
Soto, M., and D. Perea. 2011. A new specimen of Uruguaysuchus aznarezi (Crocodyliformes: Notosuchia) from the middle Cretaceous of Uruguay and its phylogenetic relationships. Zoological Journal of the Linnean Society 163. S173–S198. .
Tófalo, Ofelia; Pablo J. Pazos, and Leda Sánchez Bettucci. 2011. Estudio composicional de sedimentitas silicoclásticas y paleosuelos de la Formación Mercedes (Cretácico Superior), Uruguay. Revista de la Asociación Geológica Argentina 68. 615–626. Accessed 2020-08-23.
Soto, M.; D. Perea; G. Veroslavsky; A. Rinderknecht; M. Ubilla, and G. Lecuona. 2009. Nuevos hallazgos de restos de dinosaurios y consideraciones sobre la edad de la Formación Guichón - New findings of dinosaur remains and considerations on the age of the Guichón Formation. Revista Sociedad Uruguaya de Geología 15. 11–23. Accessed 2018-09-07.
Weishampel, David B.; Peter Dodson, and Halszka Osmólska (eds.). 2004. The Dinosauria, 2nd edition, 1–880. Berkeley: University of California Press. Accessed 2019-02-21. ISBN 0-520-24209-2
Mones, A. 1972. Lista de los vertebrados fósiles del Uruguay, I. Chondrichthyes, Osteichthyes, Reptilia, Aves - List of the fossil vertebrates of Uruguay, I. Chondrichthyes, Osteichthyes, Reptilia, Aves. Comunicaciones Paleontologicas del Museo de Historia Natural de Montevideo 1. 23–35. .
von Huene, F. 1934. Neue Saurier-Zähne aus der Kreide von Uruguay - New saurian teeth from the Cretaceous of Uruguay. Centralblatt für Mineralogie, Geologie und Paläontologie, Abteilung B: Geologie und Paläontologie 1934. 183–189. .

[dinosaurdistribution-1] Weishampel et al., 2004, pp.517-607

[FW-2] Guichón at Fossilworks.org

[Soto2009_p13-3] Soto et al., 2009, p.13

[Tofalo2011-p616-4] Tofalo et al., 2011, p.616

[Tofalo2011-p617-5] Tofalo et al., 2011, p.617

[Soto2009_p19-6] Soto et al., 2009, p.19

[Udelartitan-7] Soto, M.; Carballido, J. L.; Langer, M. C.; Silva Junior, J. C. G.; Montenegro, F.; Perea, D. (2024). "Phylogenetic relationships of a new titanosaur (Dinosauria, Sauropoda) from the Upper Cretaceous of Uruguay". Cretaceous Research. 105894. doi:10.1016/j.cretres.2024.105894.

[Mones1972-8] Mones, 1972

[Soto2011-9] Soto et al., 2011

[Soto2012-10] Soto et al., 2012

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Description[edit]

Fossil content[edit]

See also[edit]

References[edit]

Bibliography[edit]