The Chorrillo Formation, also named as Chorillo Formation,[1] is a Maastrichtian (Late Cretaceous Epoch, 72.1 - 66 million years ago) geologic formation in southern Patagonia, Argentina.

The formation is more than 50 metres (160 ft) thick and underlies the Calafate Formation and rests on top of the La Irene Formation.

[2] Dinosaur remains are among the fossils that have been recovered from the formation.

Fossils recovered from the formation are: