The taxon is represented by a single family, the Struthionidae, confined to Sub-Saharan Africa. Often regarded to comprise a single species, Struthio camelus, mitochondrial DNA seems to justify the distinction of two species, Struthio camelus (Common Ostrich) and Struthio molybdophanes (Somali Ostrich). The sister species are thought to have separated from each other by the formation of the East African Rift Valley some four million years ago.

Genus-level classification of extant Struthioniformes.

References

Freitag S, and Robinson TJ (1993), Phylogeographic patterns in mitochondrial DNA of the Ostrich (Struthio camelus), Auk 110, 612-622. (abstract)