[1] Members of this echimyid subfamily all share an origin in the eastern part of Brazil, close to the Atlantic Forest.

The teeth of Euryzygomatomyines are characterized by several features: Their zygomatic arch is reduced with a slightly concave dorsal margin, and the jugal bone is ventrally expanded with much reduced, scarcely salient inferior process.

[1] At the protein level, one amino acid replacement from leucine to proline yields a shared derived character state that is diagnostic for defining the Euryzygomatomyinae: the amino-acid proline at position homologous to site 294 of the human GHR.

[1] These phylogenetic relationships, based on the comparison of complete mitochondrial DNA genomes and nuclear DNA exons, disagree with analyses of craniodental characters which cluster together the fossorial genera Clyomys, Euryzygomatomys and Carterodon.

[3][4] Trinomys (Atlantic spiny rats) Clyomys Euryzygomatomys (guiaras) Carterodon (Owl's spiny rat) Plagiodontia Geocapromys Capromys (Desmarest's hutia) Mesocapromys Mysateles