The rodent parvorder or infraorder Phiomorpha comprises several living and extinct families found wholly or largely in Africa.

The southern continents were much more isolated leading to the unique faunas of Australia, South America, and to a lesser degree Africa.

Their success and diversification during the Oligocene is partially attributed to an early shift towards herbivory, allowing them to survive off lower-quality foods and increasing their resilience to resource instability.

Therefore, despite a decline in global temperatures and transition of African forests into savannahs and grasslands, Phiomorpha withstood this change and diversified within the new environments.

At its core lie the extant families Thryonomyidae, Petromuridae, and Bathyergidae and their extinct relatives.