Bajo de la Carpa Formation explained

Bajo de la Carpa Formation
Type:	Geological formation
Period:	Santonian
Age:	Mid-Late Santonian ~
Prilithology:	Sandstone
Otherlithology:	Mudstone, siltstone, paleosol
Region:	Neuquén & Río Negro Provinces
Country:	Argentina
Coordinates:	-38.8°N -68.8°W
Paleocoordinates:	-43.4°N -49.8°W
Unitof:	Neuquén Group  Río Colorado Subgroup
Underlies:	Anacleto Formation
Overlies:	Río Neuquén Subgroup  Plottier Formation
Thickness:	Up to 150m (490feet)
Extent:	Neuquén Basin

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]

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]

The Bajo de la Carpa Formation can reach 150m (490feet) 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.

Fossil content

Reptiles

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

• a snake-necked turtle, Lomalatachelys
• a lizard, Paleochelco
• the snake Dinilysia
• diverse crocodylomorphs occupying a range of ecological niches.

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.

Crocodylomorphs

Crocodylomorphs reported from the Bajo de la Carpa Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Barrosasuchus	B. neuquenianus^[4]
Comahuesuchus	C. brachybuccalis
Cynodontosuchus	C. rothi
Lomasuchus	L. palpebrosus.
Gasparinisuchus^[5]	G. peirosauroides
Kinesuchus	K. overoi^[6]
Neuquensuchus	N. universitas ^[7]
Notosuchus	N. lepidus
	N. terrestris
Peirosaurus	P. torminni			A fragmentary skull and a partial postcranial skeleton.

Dinosaurs

Ornithischians

Ornithischians reported from the Bajo de la Carpa Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Ankylosauria^[8]	Indetermidate.
Mahuidacursor^[9]	M. lipanglef				An ornithopod.

Sauropods

Sauropods reported from the Bajo de la Carpa Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Bonitasaura	B. salgadoi			A partial sub-adult skeleton with a lower jaw, a partial vertebrae series, and limb bones.	A titanosaur.
Inawentu	I. oslatus	Rincón de los Sauces.		A partially articulated skeleton, including a nearly complete skull, Several vertebrae from the atlas to the end of the sacrum, and both ilia	A titanosaur.
Overosaurus	O. paradasorum		Upper	A fully articulated vertebral series consists of rib bones, dorsals, and ilium.	A titanosaur.
Rinconsaurus	R. caudamirus	Rincón de los Sauces.	Lower.	The fossil remains included vertebrae, limb bones, scapula, hip bones (pubis, ilium, and ischium) and several ribs.	A titanosaur.
Traukutitan^[10]	T. eocaudata	Sitio Trauku.	Lower	A partial semi-articulated skeleton including both thigh bones and thirteen vertebrae from the anterior and middle tail.	A titanosaur.

Theropods

Theropods reported from the Bajo de la Carpa Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Achillesaurus	A. manazzonei		Upper	A partial skeleton consists of a sacral vertebra, four tail vertebrae, part of the left thighbone, shin, and foot, and the left ilium.	An alvarezsaurid.
Alvarezsaurus	A. calvoi				An alvarezsaurid.
Diuqin^[11]	D. lechiguanae	"the isthmus between the southeast coast of Lago Barreales and the northwest coast of Lago Mari Menuco"		A fragmentary but associated partial skeleton	An unenlagiine.
Llukalkan ^[12]	L. aliocranianus	La Invernada site.		A partial skull.	An abelisaur.
Neuquenornis	N. volans		Upper	A skull and a partial postcranial remains.	A enantiornithine bird.
Patagopteryx	P. eferrariisi		Upper		The oldest known flightless bird.
Tratayenia^[13]	T. rosalesi			A well-preserved partial skeleton	A megaraptoran theropod.
Velocisaurus^[14]	V. unicus				A noasaur.
Viavenator^[15]	V. exxoni				An abelisaur.

See also

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

References

Bibliography

• Coria . Rodolfo A. . Ortega . Francisco . Arcucci . Andrea B. . Currie . Philip J. . 2019 . A new and complete peirosaurid (Crocodyliformes, Notosuchia) from Sierra Barrosa (Santonian, Upper Cretaceous) of the Neuquén Basin, Argentina . 10.1016/j.cretres.2018.11.008 . . 95 . 89–105 . 2019CrRes..95...89C . 133671689 . Rodolfo Coria .
• Cruzado Caballero . P. . Gasca . J.M. . Filippi . L.S. . Cerda . I. . Garrido . A.C. . 2019 . A new ornithopod dinosaur from the Santonian of Northern Patagonia (Rincón de los Sauces, Argentina) . . 98 . 211–229 . 10.1016/j.cretres.2019.02.014. 2019CrRes..98..211C . 133830733 .
• Filippi . L.S. . Barrios . F. . Garrido . A.C. . 2018a . A new peirosaurid from the Bajo de la Carpa Formation (Upper Cretaceous, Santonian) of Cerro Overo, Neuquén, Argentina . . 83 . 75–83 . 10.1016/j.cretres.2017.10.021 . 2018CrRes..83...75F . 2019-02-21. 11336/97117 . free .
• Filippi . Leonardo S. . Méndez . Ariel H. . Gianechini . Federico A. . Juárez Valieri . Rubén D. . Garrido . Alberto C. . 2018 . Osteology of Viavenator exxoni (Abelisauridae; Furileusauria) from the Bajo de la Carpa Formation, NW Patagonia, Argentina . . 83 . 95–119 . 10.1016/j.cretres.2017.07.019 . 2018CrRes..83...95F . 11336/75315 . 2019-02-21. free .
• Fossa Mancini . E. . Egidio Feruglio . Feruglio . E. . Yussen de Campana . J.C. . 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. . Apesteguia . S. . Fernando Novas . Novas . F.E. . De la Fuente . M.S. . 2004 . Cretaceous terrestrial beds from the Neuquén Basin (Argentina) and their tetrapod assemblages . . 25 . 1 . 61–87 . 10.1016/j.cretres.2003.10.005 . 2004CrRes..25...61L . 2019-02-16.
• Lio . Gabriel . Agnolin . Federico L. . Martinelli . Agustín G. . Ezcurra . Martín D. . Fernando Novas . Novas . Fernando E. . 2018 . New specimen of the enigmatic, Late Cretaceous crocodyliform Neuquensuchus universitas sheds light on the anatomy of the species . . 83 . 62–74 . 10.1016/j.cretres.2017.09.014 . 2018CrRes..83...62L . 2019-02-21. 11336/94889 . free .
• Martinelli . Agustín G. . Sertich . Joseph J.W. . Garrido . Alberto C. . Praderio . Ángel M. . 2012 . A new peirosaurid from the Upper Cretaceous of Argentina: Implications for specimens referred to Peirosaurus torminni Price (Crocodyliformes: Peirosauridae) . . 37 . 191–200 . 10.1016/j.cretres.2012.03.017 . 2012CrRes..37..191M . 2019-02-21.
• Porfiri . Juan D. . Juárez Valieri . Rubén D. . Santos . Domenica D.D. . Lamanna . Matthew C. . 2018 . A new megaraptoran theropod dinosaur from the Upper Cretaceous Bajo de la Carpa Formation of northwestern Patagonia . . 89 . 302–319 . 10.1016/j.cretres.2018.03.014 . 2018CrRes..89..302P . 134117648 . 2019-02-21.
• Sánchez . María Lidia . Heredia . Susana . Calvo . Jorge O. . 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) . . 61 . 3–18 . 2019-02-16.
• Gianechini. Federico A.. Méndez. Ariel H.. Filippi. Leonardo S.. Paulina-Carabajal. Ariana. Juárez-Valieri. Rubén D.. Garrido. Alberto C.. A New Furileusaurian Abelisaurid from La Invernada (Upper Cretaceous, Santonian, Bajo De La Carpa Formation), Northern Patagonia, Argentina.. Journal of Vertebrate Paleontology. 2021. 40. 6. e1877151. 10.1080/02724634.2020.1877151. free.

Further reading

• Leardi . Juan Martín . Pol . Diego . Zulma Brandoni de Gasparini . Brandoni de Gasparini . Zulma . 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 . . 17 . 8 . 504–521 . 10.1016/j.crpv.2018.02.002 . 2018CRPal..17..504L . 134148996 . 2019-02-21. 11336/98526 . free .

Notes and References

1. Sánchez et al., 2006
2. Fossa Mancini et al., 1938
3. Leanza et al., 2004
4. Coria et al., 2019
5. Martinelli et al., 2012
6. Filippi et al., 2018a
7. Lio et al., 2018
8. Rozadilla. Sebastián. Agnolín. Federico. Manabe. Makoto. Tsuihiji. Takanobu. Novas. Fernando E.. September 2021. Ornithischian remains from the Chorrillo Formation (Upper Cretaceous), southern Patagonia, Argentina, and their implications on ornithischian paleobiogeography in the Southern Hemisphere. Cretaceous Research. 125. 104881. 10.1016/j.cretres.2021.104881. 2021CrRes.12504881R . 0195-6671.
9. Cruzado Caballero et al., 2019
10. Filippi . Leonardo S. . Juárez Valieri . Rubén D. . Gallina . Pablo A. . Méndez . Ariel H. . Gianechini . Federico A. . Garrido . Alberto C. . 2023 . A rebbachisaurid-mimicking titanosaur and evidence of a Late Cretaceous faunal disturbance event in South-West Gondwana . Cretaceous Research . 154 . en . 10.1016/j.cretres.2023.105754 . 0195-6671.
11. Porfiri . Juan D. . Baiano . Mattia A. . dos Santos . Domenica D. . Gianechini . Federico A. . Pittman . Michael . Lamanna . Matthew C. . 2024-06-14 . Diuqin lechiguanae gen. et sp. nov., a new unenlagiine (Theropoda: Paraves) from the Bajo de la Carpa Formation (Neuquén Group, Upper Cretaceous) of Neuquén Province, Patagonia, Argentina . BMC Ecology and Evolution . 24 . 1 . 77 . 10.1186/s12862-024-02247-w . free . 38872101 . 2730-7182. 11177497 . 2024BMCEE..24...77P .
12. Filippi et al., 2018b
13. Porfiri et al., 2018
14. Filippi et al., 2018b
15. Filippi et al., 2018b