Bajo Barreal Formation

The Bajo Barreal Formation is a geological formation in the Golfo San Jorge Basin of Chubut and Santa Cruz, Argentina whose strata date back to the Middle Cenomanian to Late Turonian. The formation was first described by Teruggi & Rossetto in 1963.^[1] The sandstones, claystones, mudstones, conglomerates and tuff were deposited in a fluvial environment.^[2] The upper part of formation is laterally equivalent to the Yacimiento El Trébol and Meseta Espinosa Formation and the lower part to the Laguna Palacios, Cañadón Seco and Comodoro Rivadavia Formations. The Bajo Barreal Formation is a reservoir rock in the Golfo San Jorge Basin.^[3]

Bajo Barreal Formation
Stratigraphic range: Mid Cenomanian-Late Turonian ~97–90 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Type	Geological formation
Unit of	Chubut Group
Underlies	Lago Colhué Huapí Formation
Overlies	Castillo Formation
Lithology
Primary	Sandstone
Other	Claystone, mudstone, conglomerate, tuff
Location
Coordinates	45.3°S 69.6°W / -45.3; -69.6
Approximate paleocoordinates	51.6°S 46.7°W / -51.6; -46.7
Region	Chubut, Santa Cruz
Country	Argentina
Extent	Golfo San Jorge Basin
Type section
Named by	Teruggi & Rossetto
Year defined	1963
Bajo Barreal Formation (Argentina)

Vertebrate paleofauna

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

Indeterminate abelisauroids and titanosaurs have been recovered from the formation.

Ornithopods

Ornithopods reported from the Bajo Barreal Formation
Genus	Species	Stratigraphic position	Material	Notes	Images
Notohypsilophodon[4]	N. comodorensis[4]	Lower	"Vertebrae, partial fore- and hindlimb"[5]	An elasmarian ornithopod.

Sauropods

Sauropods reported from the Bajo Barreal Formation
Genus	Species	Stratigraphic position	Material	Notes	Images
Andesaurus[1]	A. sp.[1]	Lower		The most basal member of Titanosauria
Campylodoniscus[4][6]	C. ameghinoi[4]	Lower	Maxilla with seven teeth.[7]
Drusilasaura[8]	D. deseadensis	Upper	"four dorsal vertebrae, one sacral vertebra, six caudal vertebrae, left scapula, dorsal rib fragments, two haemapophyses and indeterminate fragments"	A titanosaur belonging to Lognkosauria
Epachthosaurus[4]	E. sciuttoi[4]	Lower	"Vertebrae [and] partial illium."[9]
Katepensaurus	K. goicoecheai	Lower	Partial skeleton	A rebbachisaurid
Rebbachisauridae[10]	Indeterminate	Lower	Dorsal vertebra	Different from Katepensaurus.
Sarmientosaurus[11]	S. musacchioi	Lower	A skull	A lithostrotian titanosaur with a skull similar to Brachiosaurus

Theropods

Theropods reported from the Bajo Barreal Formation
Genus	Species	Stratigraphic position	Material	Notes	Images
Abelisauridae[1]	Indeterminate[1]	Lower	Maxilla	Possibly distinct from Xenotarsosaurus. Estimated to be 6.21 metres (20.4 ft) long, larger than Xenotarsosaurus.[12]
Abelisauridae[13]		Lower	partial skeleton	Different from all other comparable abelisaurids, but can't be compared with Xenotarsosaurus.
Aniksosaurus[4]	A. darwini[4]	Lower		A basal coelurosaur
Megaraptoridae[14]	Indeterminate	Upper part of lower Lowermost part of upper	Two partial skeletons
Xenotarsosaurus[4]	X. bonapartei[4]	Lower	A vertebra and a nearly complete hind limb[15]	An abelisaur.

Other fossils

Other fossils found in the formation include:^[16][17][18]

• Bonapartemys bajobarrealis
• Prochelidella argentinae
• Anura indet.
• Chelonia indet.
• Crocodylia indet.
• Pterosauria indet.

See also

• List of dinosaur-bearing rock formations
• Mata Amarilla Formation, contemporaneous formation of the Austral Basin
• Lisandro Formation, contemporaneous formation of the Neuquén Basin