Bajo de la Carpa Formation

The Bajo de la Carpa Formation is a geologic formation of the Neuquén Basin that crops out in northern Patagonia, in the provinces of Río Negro and Neuquén, Argentina. It is the oldest of two formations belonging to the Río Colorado Subgroup within the Neuquén Group. Formerly, that subgroup was treated as a formation, and the Bajo de la Carpa Formation was known as the Bajo de la Carpa Member.[1]

Bajo de la Carpa Formation Stratigraphic range: Mid-Late Santonian ~86–83 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Type	Geological formation
Unit of	Neuquén Group  Río Colorado Subgroup
Underlies	Anacleto Formation
Overlies	Río Neuquén Subgroup  Plottier Formation
Thickness	Up to 150 m (490 ft)
Lithology
Primary	Sandstone
Other	Mudstone, siltstone, paleosol
Location
Coordinates	38.8°S 68.8°W
Approximate paleocoordinates	43.4°S 49.8°W
Region	Neuquén & Río Negro Provinces
Country	Argentina
Extent	Neuquén Basin
Bajo de la Carpa Formation (Argentina)

At its base, this formation conformably overlies the Plottier Formation of the older Río Neuquén Subgroup, and it is in turn overlain by the Anacleto Formation, the youngest and uppermost formation of the Neuquén Group.[2][3]

The Bajo de la Carpa Formation can reach 150 metres (490 ft) in thickness in some locations, and consists mainly of sandstones of various colors, all of fluvial origin, with thin layers of mudstone and siltstone in between. Geological features such as geodes, chemical nodules, impressions of raindrops, and paleosols (fossil soils) are commonly found in this formation as well.[1][3]

Fossil content

Comahuesuchus brachybuccalis

Notosuchus terrestris

Vertebrate fossils are abundant within the Bajo de la Carpa Formation:

• a snake-necked turtle, Lomalatachelys
• the snake Dinilysia
• diverse crocodylomorphs occupying a range of ecological niches: Comahuesuchus, Cynodontosuchus, Lomasuchus, Gasparinisuchus,[4] Neuquensuchus universitas,[5] Notosuchus, Peirosaurus, Kinesuchus overoi,[6] and Barrosasuchus neuquenianus[7]
• titanosaurian sauropods including Bonitasaura, Overosaurus, Rinconsaurus, and Traukutitan
• the ceratosaurian theropods Velocisaurus and Viavenator exxoni[8]
• the megaraptoran theropod Tratayenia rosalesi[9]
• the bird-like theropods Achillesaurus and Alvarezsaurus
• the enantiornithine bird Neuquenornis[3]
• the oldest known true flightless bird Patagopteryx
• the basal ornithopod Mahuidacursor[10]

Small nests with eggs inside, found in this formation, probably belonged to the bird Neuquenornis.[3] Fossil wasp nests have also been found in these rocks.[1][3]

See also

• List of fossil sites
• List of dinosaur bearing rock formations
• Mata Amarilla Formation, contemporaneous formation of the Austral Basin

References

1. Sánchez et al., 2006
2. Fossa Mancini et al., 1938
3. Leanza et al., 2004
4. Martinelli et al., 2012
5. Lio et al., 2018
6. Filippi et al., 2018a
7. Coria et al., 2019
8. Filippi et al., 2018b
9. Porfiri et al., 2018
10. Cruzado Caballero et al., 2019

Bibliography

• Coria, Rodolfo A.; Francisco Ortega; Andrea B. Arcucci, and Philip J. Currie. 2019. A new and complete peirosaurid (Crocodyliformes, Notosuchia) from Sierra Barrosa (Santonian, Upper Cretaceous) of the Neuquén Basin, Argentina. Cretaceous Research 95. 89–105.
• Cruzado Caballero, P.; J.M. Gasca; L.S. Filippi; I. Cerda, and A.C. Garrido. 2019. A new ornithopod dinosaur from the Santonian of Northern Patagonia (Rincón de los Sauces, Argentina). Cretaceous Research in press. _.
• Filippi, L.S.; F. Barrios, and A.C. Garrido. 2018a. A new peirosaurid from the Bajo de la Carpa Formation (Upper Cretaceous, Santonian) of Cerro Overo, Neuquén, Argentina. Cretaceous Research 83. 75–83. Accessed 2019-02-21.
• Filippi, Leonardo S.; Ariel H. Méndez; Federico A. Gianechini; Rubén D. Juárez Valieri, and Alberto C. Garrido. 2018. Osteology of Viavenator exxoni (Abelisauridae; Furileusauria) from the Bajo de la Carpa Formation, NW Patagonia, Argentina. Cretaceous Research 83. 95–119. Accessed 2019-02-21.
• Fossa Mancini, E.; E. Feruglio, and J.C. Yussen de Campana. 1938. Una reunión de geólogos de YPF y el problema de la terminología estratigráfica ("A YPF geologists' reunion and the problem of stratigraphy terminology"). Boletín de Informaciones Petroleras 15. 1–67.
• Leanza, H.A.; S. Apesteguia; F.E. Novas, and M.S. De la Fuente. 2004. Cretaceous terrestrial beds from the Neuquén Basin (Argentina) and their tetrapod assemblages. Cretaceous Research 25. 61–87. Accessed 2019-02-16.
• Lio, Gabriel; Federico L. Agnolin; Agustín G. Martinelli; Martín D. Ezcurra, and Fernando E. Novas. 2018. New specimen of the enigmatic, Late Cretaceous crocodyliform Neuquensuchus universitas sheds light on the anatomy of the species. Cretaceous Research 83. 62–74. Accessed 2019-02-21.
• Martinelli, Agustín G.; Joseph J.W. Sertich; Alberto C. Garrido, and Ángel M. Praderio. 2012. A new peirosaurid from the Upper Cretaceous of Argentina: Implications for specimens referred to Peirosaurus torminni Price (Crocodyliformes: Peirosauridae). Cretaceous Research 37. _. Accessed 2019-02-21.
• Porfiri, Juan D.; Rubén D. Juárez Valieri; Domenica D.D. Santos, and Matthew C. Lamanna. 2018. A new megaraptoran theropod dinosaur from the Upper Cretaceous Bajo de la Carpa Formation of northwestern Patagonia. Cretaceous Research 89. 302–319. Accessed 2019-02-21.
• Sánchez, María Lidia; Susana Heredia, and Jorge O. Calvo. 2006. Paleoambientes sedimentarios del Cretácico Superior de la Formación Plottier (Grupo Neuquén), Departamento Confluencia, Neuquén (Sedimentary paleoenvironments in the Upper Cretaceous Plottier Formation (Neuquen Group), Confluencia, Neuquén). Revista de la Asociación Geológica Argentina 61. 3–18. Accessed 2019-02-16.

Further reading

• Leardi, Juan Martín; Diego Pol, and Zulma Brandoni de Gasparini. 2018. New Patagonian baurusuchids (Crocodylomorpha; Notosuchia) from the Bajo de la Carpa Formation (Upper Cretaceous; Neuquén, Argentina): New evidences of the early sebecosuchian diversification in Gondwana. Comptes Rendus Palevol 17. 504–521. Accessed 2019-02-21.