Owen's Bidentalia was equivalent to Dicynodontia, which today is used as a much larger group encompassing all dicynodonts. In its current use, Bidentalia includes two major subgroups, Cryptodontia and Dicynodontoidea. Bidentalia originated in the Guadalupian epoch of the Permian and quickly spread worldwide, with early species known from both Brazil and Russia. However, they were conspicuously absent from Africa despite its well-known Permian fauna until the late Permian. The oldest and most basal known bidentalian is "Rastodon". Bidentalia is divided into two major groups, the Cryptodontia and the Dicynodontoidea, as well as a small number of basal genera such as "Elph" and "Rastodon" However, the Cryptodontia may be paraphyletic. Below is a cladogram showing the phylogeny of Bidentalia from a recent study, Kammerer "et al." (2011):