The Paso del Sapo Formation is a Maastrichtian geologic formation of the Cañadón Asfalto Basin in Argentina. The siltstones of the formation were deposited in a lacustrine environment. Plesiosaur remains are among the fossils that have been recovered from its strata.

• Aristonectes parvidens
• Ptychoceratodus sp.
• Flora

• Plesiosaur stratigraphic distribution