Earth:Candeleros Formation

Candeleros Formation Stratigraphic range: early Cenomanian ~99–97 Ma PreЄ Є O S D C P T J K Pg N ↓
Candeleros Formation near Cerro El Vagon, Neuquen, Argentina
Type	Geological formation
Unit of	Neuquén Group  Río Limay Subgroup
Underlies	Huincul Formation
Overlies	Lohan Cura Formation
Thickness	300 m (980 ft)
Lithology
Primary	Eolian sandstone
Other	Conglomerate, siltstone, paleosol
Location
Coordinates
Paleocoordinates	[ ⚑ ] 46.5°S 45.5°W / -46.5; -45.5
Region	Mendoza, Neuquén & Río Negro Provinces
Country	Argentina
Extent	Neuquén Basin
Type section
Named for	Candeleros Hill
Named by	Wichmann
Year defined	1929
Candeleros Formation (Argentina)

The Candeleros Formation (formerly known as the Candeleros Member of the "Río Limay Formation") is a geologic formation that crops out in the Río Negro, Neuquén, and Mendoza provinces of northern Patagonia, Argentina . It is the oldest formation in the Neuquén Group and belongs to the Rio Limay Subgroup. Formerly that subgroup was treated as a formation, and the Candeleros Formation was known as the Candeleros Member.

Description

The type locality of the Candeleros Formation is Candeleros Hill in Neuquén Province, after which the formation was named by Wichmann in 1929. This formation unconformably overlies the Lohan Cura Formation, and it is in turn overlain by the Huincul Formation, also a unit of the Neuquén Group. The sediments of the latter are of lighter greenish and yellow colors and the boundary between the Candeleros and Huincul formations is easily recognizable.

The Candeleros Formation is almost 300 metres (980 ft) thick in some sections. Overall, the formation represents a part of the ancient Kokorkom desert with braided river system, made up mostly of sandstones and conglomerates. There are also isolated sections that represent eolian (wind-blown) deposition, as well as siltstones deposited under swamp conditions. Paleosols (soil deposits) are common in some sections as well.

Fossil content

The Candeleros Formation has a very diverse fossil fauna, including:

• dipnoan fish (including Ceratodus argentinus)
• frogs (including Avitabatrachus)
• Rhynchocephalians (including Priosphenodon avelasi and Tika giacchinoi)
• primitive snakes (including Najash rionegrina)
• several turtles (including 2 species of Prochelidella)
• an azhdarchid pterosaur, the oldest known from South America
• rebbachisaurid sauropods (Limaysaurus, Nopcsaspondylus and Rayososaurus)
• titanosaurian sauropods (including Andesaurus and a second unnamed huge titanosaur)
• abelisaurid theropods (Ekrixinatosaurus and unnamed form)
• a carcharodontosaurid (Giganotosaurus)
• a dromaeosaurid theropod (Buitreraptor gonzalezorum)
• an alvarezsauroid theropod (Alnashetri)
• a basal coelurosaur (Bicentenaria)
• Iguanodonts (including Bonaparteichnium)
• a notosuchian (Araripesuchus)
• a basal thyreophoran (Jakapil)
• cladotherian mammals (including Cronopio dentiacutus)
• ichnofossils of Sousaichnum monettae, Limayichnus major, Bonaparteichnum tali, Bressaniichnus patagonicus, Deferraiichnum mapuchense, Abelichnus astigarragae and Picunichnus benedettoi

In 2021, fossil material of a giant titanosaur sauropod, distinct from Andesaurus and probably exceeding Patagotitan in size, was described from the formation by Otero et al. (2021).

Amphibians

Frogs

Taxa	Species	Locality	Stratigraphic position	Material	Notes	Images
Avitabatrachus	A. uliana				A Pipimorpha frog.

Rhynchocephalians

Taxa	Species	Locality	Stratigraphic position	Material	Notes	Images
Priosphenodon	P. avelasi				A Rhynchocephalian.
Tika	T. giacchinoi				A Rhynchocephalian.

Fish

Taxa	Species	Locality	Stratigraphic position	Material	Notes	Images
Ceratodus	C. argentinus				A lungfish.

Dinosaur

Ornithischian

Taxa	Species	Locality	Stratigraphic position	Material	Notes	Images
Bonaparteichnium	B. tali			Footprints.	An Iguanodont.
Jakapil	J. Kaniukura			MPCA-PV-630, a partial skeleton including several osteoderms and a complete lower jaw.	A Thyreophora ornithopod.

Saurischian

Sauropod

Taxa	Species	Locality	Stratigraphic position	Material	Notes	Images
Andesaurus	A. delgadoi				A titanosaur.
Limaysaurus	L. tessonei'				A rebbachisaurid sauropod.
Nopcsaspondylus	N. alarconensis				A rebbachisaurid sauropod.
Rayososaurus	R. agrioensis				A rebbachisaurid sauropod.
Titanosauria	indeterminate.

Theropod

Taxa	Species	Locality	Stratigraphic position	Material	Notes	Images
Abelichnus	A. astigerrae
Alnashetri	A. cerropoliciensis				An alvarezsauroid theropod.
Bicentenaria	B. argentina				A coelurosaur.
Buitreraptor	B. gonzalezorum				A dromaeosaurid theropod.
Ekrixinatosaurus	E. novasi				An Abelisaurid theropod.
Giganotosaurus	G. carolinii			A skeletal specimen.	A carcharodontosaurid theropod.

Mammals

Taxa	Species	Locality	Stratigraphic position	Material	Notes	Images
Cronopio	C. dentiacutus	La Buitrera.	Neuquén Group.	MPCA PV 454, a partial skull without skull roof, basicranium, and squamosals, and from the referred specimens MPCA PV 450, a partial left lower jaw with damaged teeth, and MPCA PV 453, an incomplete skull with a relatively complete right lower jaw missing some teeth.	A small insectivorous mammal that belongs to the Meridiolestida family.

Reptiles

Taxa	Species	Locality	Stratigraphic position	Material	Notes	Images
Araripesuchus	A. buitreraensis
Najash	N. rionegrina

See also

• List of fossil sites
• Bajo Barreal Formation, contemporaneous fossiliferous formation of the San Jorge Basin
• Cerro Fortaleza Formation, contemporaneous fossiliferous formation of the Austral Basin
• Alcântara Formation, contemporaneous fossiliferous formation of the São Luís-Grajaú Basin, Brazil
• List of dinosaur bearing rock formations

References

Bibliography

• Otero, A.; Carballido, J. L.; Salgado, L.; Canudo, J. I.; Garrido, A. C. (2021). "Report of a giant titanosaur sauropod from the Upper Cretaceous of Neuquén Province, Argentina". Cretaceous Research 122: Article 104754. doi:10.1016/j.cretres.2021.104754.  doi:10.1016/j.cretres.2021.104754
• Canale, Juan I.; Cerda, Ignacio; Novas, Fernando E.; Haluza, Alejandro (2016). "Small-sized abelisaurid (Theropoda: Ceratosauria) remains from the Upper Cretaceous of northwest Patagonia, Argentina". Cretaceous Research 62: 18–28. doi:10.1016/j.cretres.2016.02.001.  doi:10.1016/j.cretres.2016.02.001
• 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)". Revista de la Asociación Geológica Argentina 61: 3–18. https://www.researchgate.net/publication/262615949. Retrieved 2019-02-16. 
• Leanza, H.A.; Apesteguia, S.; Novas, F.E.; De la Fuente, M.S. (2004). "Cretaceous terrestrial beds from the Neuquén Basin (Argentina) and their tetrapod assemblages". Cretaceous Research 25: 61–87. doi:10.1016/j.cretres.2003.10.005. https://www.researchgate.net/publication/257047651. Retrieved 2019-02-16. 
• Leonardi, Giuseppe (1994). "Annotated Atlas of South America Tetrapod Footprints (Devonian to Holocene) with an appendix on Mexico and Central America". Ministerio de Minas e Energia - Companhia de Pesquisa de Recursos Minerais, Geological Service of Brazil. pp. 1–248. https://www.researchgate.net/publication/309643073. Retrieved 2019-03-25. 
• Wichmann, R (1929). "Los Estratos con Dinosaurios y su techo en el este del Territorio del Neuquén ("The dinosaur-bearing strata and their upper limit in eastern Neuquén Territory")". Dirección General de Geología, Minería e Hidrogeología Publicación 32: 1–9.