The forms to be included in the taxon Anomodontia are the Dinocephalia and Dicynodontia. The latter, as explained below, is here used to include the Venjukovioidea and the Dromasaroidea, as well as the 'higher' dicynodonts (Eodicynodontoidea, Endothiodomoidea, Pristerodontoidea, etc.) These are all Permian or Triassic mammallike retiles. Various views concerning the relationships and origins of these forms have been expressed in the past. It is assumed that they have all arisen from the pelycosaurs, probably from the sphenacodonts, but little positive evidence underlies this assertion. However, with no evidence to the contrary this will also be the view adopted in the present work. ROMER 1966 expressed the relationships of the four forms as Suborder Anomodontia Infraorder Dinocephalia Infraorder Venjukoviamorpha Infraorder Dromasauria Infraorder Dicynodontia Strictly speaking the term "Amonodontia" was erected by OWEN 1859 for animals without teeth, except possibly tusks or caniniform processes, with a parietal foramen, with two nostrils and a fixed tympanic pedicle. He included three families within the order: the Dicynodontia (Dicynodon and Ptychognathus (Lystrosaurus)), the Cryptodontia (Oudenodon) and the Gnathodontia (Rhynchocephalus). In 1861 OWEN modified this classification, excluding the Gnathodontia and including the Cynodontia for forms like Galesaurus. OWEN 1876a again modified this classification, renaming the Dicynodontia the Bidentalia and including only this familiy, the Cryptodontia and a new family, the Endothiodontia (for Endothiodon). SEELEY 1889, 1894 b, NICHOLSON & LYDEKKER 1899 and LYDEKKER 1890 a included further families within the Anomodontia, but BROOM 1905 b stressed that many of these families did not fall within the original definition which Owen used for the Anomodontia, and Broom suggested that only forms allied to Dicynodon (i. e. Oudenodon, Lystrosaurus, etc.) should be included. In other words, "Anomodontia" as originally envisaged is equivalent to the group that the present work calls "Dicynodontia". It was not until WATSON & RoMER's 1956 classification that some of the dinocephalians were also included in the Anomodontia, and not until 1966 that all of the dinocephalians were included. Even though, strictly speaking, it may be unjustifiable, the present work will follow the latter practice to avoid substitution of the well-used term Dicynodontia with the more confused Anomodontia, and to preclude the necessity of erecting a new name for the category that includes these forms and the dinocephalians. Although (as will be demonstrated below) the present work will follow a very similar scheme to ROMER 1966, not all authors in the past have done so. As far as the dinocephalians are concerned few opinions have been expressed concerning their origin, although it is generally felt that the later dinocephalians can be derived from pelycosaurs (presumably phenacodontids) via the brithopodines ( see, for example, BOONSTRA 1972). …
