Lomasuchus is an extinct genus of peirosaurid notosuchian known from the Late Cretaceous (Santonian stage) of Neuquén Province, western central Argentina. It contains a single species, Lomasuchus palpebrosus. Lomasuchus lends its name to a subfamily of peirosaurids called the Lomasuchinae. Lomasuchinae was constructed in 2004 and included Lomasuchus (the type genus), and a tribe called Mahajangasuchini, which included Mahajangasuchus and Uberabasuchus. Mahajangasuchus is now placed outside Peirosauridae in a different family, Mahajangasuchidae.