Candeleros Formation

__NOTOC__The Candeleros Formation is a geologic formation that outcrops in Río Negro, Neuquén, and Mendoza provinces of Argentina. It is the oldest formation in the Neuquén Group and belongs to the Río Limay Subgroup. Formerly that subgroup was treated as a formation, and the Candeleros Formation was known as the Candeleros Member.Sánchez "et al." (2006)]

The type locality of the Candeleros Formation is Candeleros Hill in Neuquén province [Wichmann (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 [Leanza "et al." (2004)] .

The Candeleros Formation is almost 300 meters thick in some sections. Overall, the formation represents an ancient 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. [Leanza "et al." (2004), Sánchez "et al." (2006)]

Age

Era: Mesozoic
Period: Late Cretaceous
Faunal stage: early Cenomanian
Absolute Age: ~100 to ~97 mya

Paleontology

The Candeleros Formation has a very diverse fossil fauna, including:
* fish
* frogs
* sphenodontians
* primitive snakes (including "Najash")
* several turtles (including 2 species of "Prochelidella")
* abundant crocodilians (including a species of "Araripesuchus")
* rebbachisaurid sauropods ("Limaysaurus" and "Nopcsaspondylus")
* titanosaurian sauropods {including "Andesaurus")
* a carcharodontosaurid theropod ("Giganotosaurus")
* a dromaeosaurid theropod ("Buitreraptor")
* cladotherian mammals

There are also several trackway sites and eggshells known from the Candeleros Formation, including theropods, sauropods, ornithopods, and pterosaurs.

One of the most productive fossil localities in the Candeleros is known as "La Buitrera" and is now well-known for producing many small tetrapod skeletons with three-dimensional preservation, although larger fossils, such as dinosaurs, are rare. Much larger dinosaur fossils have been recovered from other sites in the formation, however, including one of the largest carnivores known, "Giganotosaurus". "La Buitrera" means, roughly, "the vulture-roost"; the genus "Buitreraptor", a small bird-like dinosaur that must have been a predator of small vertebrates and possibly a scavenger was named after this.

ee also

* List of fossil sites

Footnotes

References

* (2004): Cretaceous terrestrial beds from the Neuquén Basin (Argentina) and their tetrapod assemblages. "Cretaceous Research" 25(1): 61-87. doi|10.1016/j.cretres.2003.10.005 (HTML abstract)
* (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(1): 3-18. [http://www.scielo.org.ar/pdf/raga/v61n1/v61n1a01.pdf PDF fulltext]
* (1929): Los Estratos con Dinosaurios y su techo en el este del Territorio del Neuquén ["The dinosaur-bearing strata and their upper limit in estern Neuquén Territory"] . "Dirección General de Geología, Minería e Hidrogeología Publicación" 32: 1-9.