The Río Belgrano Formation is a Barremian to Aptian geologic formation of the Austral Basin in Patagonia, southern Argentina. Among others, pterosaur and ichthyosaur fossils have been recovered from the formation.

The following fossils have been recovered from the formation:

• Hatchericeras patagonense
• Palaeastacus terraereginae
• Platypterygius hauthali
• Sanmartinoceras africanum
• Tonohamites aequicingulatus
• ?Anhangueridae indet.

• List of pterosaur-bearing stratigraphic units

• Páramo Fonseca, María Eurídice (2018), "Restos apendiculares de un ictiosaurio oftalmosáurido del Barremiano inferior de Villa de Leiva, Colombia", Boletín de Geología, 40: 15–30, doi:10.18273/revbol.v40n1-2018001, retrieved 2019-02-06

• M. B. Aguirre Urreta. 1989. The Cretaceous decapod Crustacea of Argentina and the Antarctic Peninsula. Palaeontology 32(3):499-552
• M. B. Aguirre Urreta. 1986. Aptian ammonites from the Argentinian Austral Basin. The Subfamily Helicancylinae Hyatt, 1894. Annals of the South African Museum 96(7):271-314
• J. F. Bonaparte. 1978. El Mesozoico de America de Sur y sus Tetrapodos [The Mesozoic of South America and its tetrapods]. Opera Lilloana 26:1-596