Euryzygomatomys is a genus of South American rodents, commonly called guiaras, in the family Echimyidae. It contains two extant and one fossil species, found in Argentina, Brazil and Paraguay. They are as follows:

• Brandt's guiara (Euryzygomatomys guiara)
• Fischer's guiara (Euryzygomatomys spinosus)
• †Euryzygomatomys hoffstetteri Goeldi 1901 - Tarija Formation, Bolivia

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