Bajada Colorada Formation

The Bajada Colorada Formation is a geologic formation of the southern Neuquén Province in the Neuquén Basin of northern Patagonia, Argentina. The formation belongs to the Mendoza Group and is Late Berriasian to Early Valanginian in age. The formation is renowned for preserving fossil remains of Bajadasaurus pronuspinax, a genus of dicraeosaurid dinosaurs named after the formation.

Bajada Colorada Formation
Stratigraphic range: Late Berriasian-Early Valanginian ~140–134 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Type	Geological formation
Unit of	Mendoza Group
Underlies	Agrio Formation
Overlies	Quintuco & Picún Leufú Formations
Lithology
Primary	Sandstone, conglomerate
Other	Siltstone, claystone
Location
Coordinates	39.8°S 69.7°W / -39.8; -69.7
Approximate paleocoordinates	38.8°S 32.2°W / -38.8; -32.2
Region	Neuquén Province
Country	Argentina
Extent	Neuquén Basin
Type section
Named by	Roll
Year defined	1939
Bajada Colorada Formation (Argentina)

Description

The Bajada Colorada Formation, first defined by Roll in 1939, pertains to the Mendoza Group.^[1] It overlies the Quintuco and Picún Leufú Formations and is overlain by the Agrio Formation. The contact with the Agrio Formation is discordant and the unconformity has been dated to 134 Ma.^[2] The formation is laterally equivalent with the Mulichinco Formation.^[3] The formation comprises red and greenish-brown, fine to coarse grained conglomerates and thick-bedded sandstones with well-developed bands of light brown siltstones and reddish, pinkish grey and purple-reddish claystones.^[4] The formation was deposited in a fluvial environment, and the paleoenviroment resembled a braided river system with well-preserved channels and paleosols.^[5]

X-ray diffraction studies of sediments belonging to the Bajada Colorada Formation have revealed the presence of smectite, chlorite, illite and kaolinite.^[1]

Fossil content

The formation has provided fossils of:^[6]

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Dinosaurs

Ornithischians

Ornithischians of the Bajada Colorada Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Ankylosauria Indet.[7]	Indeterminate

Sauropods

Sauropods of the Bajada Colorada Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Bajadasaurus[8]	B. pronuspinax				A dicraeosaurid sauropod
Leinkupal[9]	L. laticauda				A diplodocine diplodocid
Ninjatitan[10]	N. zapatai				A titanosaurian sauropod

Theropods

Theropods of the Bajada Colorada Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Abelisauridae Indet.[11]	Indeterminate
Abelisauroidea Indet.	Indeterminate
Deinonychosauria Indet.	Indeterminate
Tetanurae Indet.	Indeterminate

See also

• List of dinosaur-bearing rock formations
• Baños del Flaco Formation, contemporaneous formation of the Mendoza Group in Chile
• Chon Aike Formation, contemporaneous formation of central Patagonia