Bajo de la Carpa Formation

Bajo de la Carpa Formation
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°48′S 68°48′W / 38.8°S 68.8°W
Approximate paleocoordinates	43°24′S 49°48′W / 43.4°S 49.8°W
Region	Neuquén & Río Negro Provinces
Country	Argentina
Extent	Neuquén Basin
	Bajo de la Carpa Formation (Argentina)

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]^[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

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]

References

^ ^a ^b ^c Sánchez et al., 2006
^ Fossa Mancini et al., 1938
^ ^a ^b ^c ^d ^e Leanza et al., 2004
^ Martinelli et al., 2012
^ Lio et al., 2018
^ Filippi et al., 2018a
^ Coria et al., 2019
^ Filippi et al., 2018b
^ Porfiri et al., 2018
^ Cruzado Caballero et al., 2019

Bajo de la Carpa Formation

Fossil content

See also

References

Bibliography

Further reading