Huincul Formation

The Huincul Formation is a geologic formation that outcrops in Río Negro and Neuquén provinces of Argentina. It is the second formation in the Río Limay Subgroup, the oldest subgroup within the Neuquén Group. Formerly that subgroup was treated as a formation, and the Huincul Formation was known as the Huincul Member.

The type locality of the Huincul Formation is near the town of Plaza Huincul in Neuquén province. This formation conformably overlies the Candeleros Formation, and it is in turn overlain by the Lisandro Formation.

The Huincul Formation is thought to represent an arid environment with ephemeral or seasonal streams. In some areas, it is up to 250 meters thick. It is mainly composed of green and yellow sandstones and can easily be differentiated from the overlying Lisandro Formation, which is red in color. The Candeleros Formation, underlying the Huincul, is composed of darker sediments, making all three formations easily distinguishable.

Age
Era: Mesozoic Period: Late Cretaceous Faunal stage: late Cenomanian Absolute Age: ~97 to ~94 mya

Paleontology
Fossil bones are rarely found in the Huincul Formation. However, remains of the largest land animal known, Argentinosaurus huinculensis, were found in the Huincul Formation, and this species is named after it. One of the largest predators known, Mapusaurus, has also been recovered from a bonebed in this formation.

Animal fossils found in the Huincul Formation include:
 * several titanosaurian sauropods (including Argentinosaurus)
 * a rebbachisaurid sauropod (Cathartesaura)
 * a carcharodontosaurid theropod (Mapusaurus)
 * abelisauroid theropods (including Ilokelesia)
 * several ornithopods