Sphagesaurus is an extinct genus of sphagesaurid notosuchian crocodylomorph from the Late Cretaceous of southwest São Paulo, southern Brazil.

The specimen was collected at the sediments of the Adamantina Formation during the construction of the new railroad station of Buenopolis city of São Paulo.

It was named by Marco Brandalise de Andrade and Reinaldo J. Bertini in 2008, on the basis of MPMA 15-001/90, a nearly complete skull and mandible preserved in occlusion.

It was collected from the Bairro Cachoeira locality at the base of the Serra da Água Limpa, about 8 km northwest of Monte Alto city of northern São Paulo, from the Adamantina Formation.

It was found on the São Francisco Farm, in Homem de Mello, the rural area of Monte Alto County, also from the Adamantina Formation.