This taxon was originally named by Huene (1908) on the basis of Ornithosuchus and subsequently used by many workers (e.g. Steel 1970) to include various saurischian dinosaurs. Steel (1970) included Ornithosuchus along with several dubious tooth-based taxa (Basutodon, Picrodon, Palaeosauriscus, Cladeiodon, Zatomus, and Teratosaurus). Today, this taxon is restricted to Ornithosuchus and its closest relatives, a small clade at the base of Crurotarsi.

The active definition is a second-order revision of the initial definition for the taxon in Sereno (1991). Benton (2004) more recently proposed a confusing definition that includes a combination of node- and stem-based phraseology. It is not necessarily a node-based definition, because  inclusion of the common ancestor of the identified clade is not clear.  A stem-based definiton is adopted here using appropriate external specifiers. Such a definition will ensure the inclusion of newfound basal taxa most closely related to known ornithosuchids.