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.[1]
The type locality of the Candeleros Formation is Candeleros Hill in Neuquén Province, after which the formation was named by Wichmann in 1929.[2] 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.[3]
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.[1][3]
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).[9]
The holotype consists of a partial left femur, distal portions of left and right tibiae, right fibula, proximal tarsals of both ankles, a nearly complete right metatarsus, proximal and distal parts of the left metapodials, and left pedal digit III.
Several paratypes consist of fragments of two premaxillae with three pairs of teeth; a piece of upper right jawbone with a tooth; pieces of seventeen vertebrae; fourteen sacral vertebrae; twenty caudal vertebrae; pieces of two shoulder blades; an upper back corner of a right raven's jawbone; the tops of three ulna; the end of a spoke bone; eight hand claws; pieces of a left femur; five upper shafts of pubic bones; five partial femurs; the tops of two left tibias; the underside of a right tibia; a right tibia; pieces of five metatarsals; fifteen phalanges, separately eight-foot claws and pieces of rib.
A partial skull, and a disarticulated postcranial skeleton which includes a vertebral column, pectoral and pelvic girdles, the femora, and the left tibia and fibula.
Paratypes consist of a partial skull without skull roof, basicranium, and squamosals, a partial left lower jaw with damaged teeth, and an incomplete skull with a relatively complete right lower jaw missing some teeth.
A small insectivorous mammal that belongs to the Meridiolestida family.
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.
