The Rio Limay Subgroup is a geological unit in Neuquen, Argentina whose strata date back to the Late Cretaceous

Late Cretaceous

The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...

. Dinosaur remains are among the fossils that have been recovered from the formations it contains.

Having previously been considered a distinct formation, the Rio Limay Subgroup is now considered a member of the larger Neuquén Group

Neuquén Group

The Neuquén Group is a group of geologic formations found in Argentina. Rocks in the Neuquén Group fall within the Cenomanian to early Campanian stages of the Late Cretaceous Period, about 100 million to 80 million years in age...

, and itself contains several specific geological formations (from youngest to oldest):

• Cerro Lisandro Formation
  Cerro Lisandro Formation
  The Lisandro Formation, alternatively known as the Cerro Lisandro Formation, is a geologic formation with outcrops in the Neuquén province of Argentina. It is the youngest formation within the Río Limay Subgroup, the lowest section of the Neuquén Group...
  
   (late Cenomanian to early Turonian)
• Huincul Formation
  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...
  
   (late Cenomanian)
• Candeleros Formation
  Candeleros Formation
  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 Rio Limay Subgroup...
  
  (early Cenomanian)