The Candeleros 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.

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 fused with the Huincul Formation, also a unit of the Neuquén Group. The sediments of the latter are of lighter greenish and yellow colors and the fused 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.

The Candeleros Formation has a very diverse fossil fauna, including fish, frogs, mammals, rhynchocephalians, snakes, turtles, notosuchians, pterosaurs, and abundant dinosaurs including rebbachisaurid and titanosaurian sauropods and diverse theropods, and the enigmatic armored Jakapil.

Ichnofossils found in the formation include those assigned to Sousaichnum monettae, Limayichnus major, Bressaniichnus patagonicus, Deferraiichnum mapuchense, and Picunichnus benedettoi.

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.

Taxa	Species	Locality	Member	Material	Notes	Images
Ceratodus	C. argentinus		Upper		A lungfish

Taxa	Species	Locality	Member	Material	Notes	Images
Avitabatrachus	A. uliana	El Gigante	Lower	Fragmentary skull and postcranial skeleton	A pipimorph frog

Taxa	Species	Locality	Member	Material	Notes	Images
Bonaparteichnium	B. tali			Footprints	Iguanodont ichnofossils
Jakapil	J. kaniukura	Cerro Policía	Upper	A partial skeleton including several osteoderms and a complete lower jaw	Possibly a basal thyreophoran

Sauropods

Taxa	Species	Locality	Member	Material	Notes	Images
Andesaurus	A. delgadoi		Lower	A partial skeleton	A basal titanosaur
Campananeyen	C. fragilissimus	Barda Atravesada de Las Campanas	Lower	A fragmentary skeleton	A rebbachisaurid
Limaysaurus	L. tessonei		Upper		A rebbachisaurid
Nopcsaspondylus	N. alarconensis				A rebbachisaurid
Rayososaurus	R. agrioensis	Agrio del Medio	Upper	A left scapula, an almost complete right scapular blade, and the distal three-quarters of a left femur.	A rebbachisaurid
Titanosauria	Indeterminate		Upper		A giant titanosaur; possibly Argentinosaurus

Theropods

Taxa	Species	Locality	Member	Material	Notes	Images
Abelichnus	A. astigerrae			A footprint
Alnashetri	A. cerropoliciensis	La Buitrera	Upper	A fragmentary skeleton including leg and foot bones	An alvarezsauroid
Bicentenaria	B. argentina	Ezequiel Ramos Mexia Reservoir	Upper	Much of a skeleton	A coelurosaur
Buitreraptor	B. gonzalezorum	La Buitrera	Upper	Several partial skeletons	A dromaeosaurid
Ekrixinatosaurus	E. novasi	Bajo del Añelo	Upper	A partial skeleton	An abelisaurid
Giganotosaurus	G. carolinii	Los Candeleros and Villa El Chocón	Upper/Lower	A partial skull and a disarticulated postcranial skeleton	A carcharodontosaurid

Taxa	Species	Locality	Member	Material	Notes	Images
Azhdarchidae	Indeterminate	Ezequiel Ramos Mexía Reservoir	Upper	A partial cervical vertebra	An azhdarchid

Taxa	Species	Locality	Member	Material	Notes	Images
Araripesuchus	A. buitreraensis	La Buitrera, Cerro Policía and El Pueblito.	Upper	Multiple skull specimens.	A small notosuchian crocodyliform
	A manzanensis		Upper	A partial skull and lower jaw
	A. patagonicus	El Chocón.	Lower	An anterior half of the skull with an articulated mandible, lacking the most anterior portion of the rostrum and also preserves part of the postcranium
Najash	N. rionegrina		Upper		A basal snake
Priosphenodon	P. avelasi		Upper		An eilenodontine rhynchocephalian
Tika	T. giacchinoi		Upper		A sphenodontine rhynchocephalian

Taxa	Species	Locality	Member	Material	Notes	Images
Cronopio	C. dentiacutus	La Buitrera	Upper	Skull bones and teeth	A small meridiolestidan mammal

Taxa	Species	Locality	Member	Material	Notes	Images
Prochelidella	P. buitreraensis		Upper		A small chelid turtle
Elkanemys	E. pritchardi		Upper		A bothremydid turtle

• 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

• 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. Bibcode:2021CrRes.12204754O. doi:10.1016/j.cretres.2021.104754. S2CID 233582290. 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. Bibcode:2016CrRes..62...18C. doi:10.1016/j.cretres.2016.02.001. hdl:11336/59930. 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. 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 (1): 61–87. Bibcode:2004CrRes..25...61L. doi:10.1016/j.cretres.2003.10.005. 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. 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.