La Colonia Formation

The La Colonia Formation is a geological formation in Argentina whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation.
Originally thought to be Campanian (c.73-72 million years ago) in age or earlier, studies of underlying formations have made a Maastrichtian (70–66 million years ago) age more likely.
It is divided up into three distinct facies, the first is up to thick and consists of conglomerate, the second is by far the thickest at over , consists of siltstone and claystone, with interbeds of claystone/shale and sandstone, the third is less than thick and consists of clay, and probably represents a nearshore marine environment.
Flora.
The paleoflora was known for its aquatic components, "Paleoazolla" and "Regnellidium". However, recent paleobotanical discoveries at the Cañadón del Irupé locality have revealed the presence of a more diverse range of plants associated with these water bodies, including pteridophytes, gymnosperms, and various angiosperms. Among these are fossil leaves and fruits assignable to Nelumbonaceae.
Fossil content.
Mammals.
Over 300 mammal specimens have been found in the La Colonia Formation.