Guichón_Formation
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]
| Guichón Formation | |
|---|---|
| Stratigraphic range: Aptian-Santonian ~125–85 Ma | |
| 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 | 32.0°S 57.7°W / -32.0; -57.7 |
| Approximate paleocoordinates | 38.4°S 30.0°W / -38.4; -30.0 |
| Region | Paysandú Department |
| Country |  Uruguay |
| Extent | Norte Basin |
| Type section | |
| Named for | Guichón |
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]
The following fossils have been reported from the formation:[2][6]
- Fossil eggs
- Weishampel et al., 2004, pp.517-607
- 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
- Soto et al., 2011
- Soto et al., 2012
Bibliography
- 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. .