First described by paleontologist T. H. Barry in 1974, E. oosthuizeni is named after Roy Oosthuizen, the South African farmer who discovered the type specimen (a partial skull without the mandible) on his Cape Province farm between 1964 and 1970.

While the premaxillary bones are fused in more derived dicynodonts, a thin suture extending dorsally up from the palatal facet reveals that they are paired in Eodicynodon, an ancestral feature they share with their primitive relatives Venyukovia, Otsheria, and Pelycosauria.

[3] The South African Karoo Supergroup is a fossil-rich series of bedded shales that was continuously deposited beginning in the late Carboniferous through the early Jurassic.

From 1964 to 1970, the farmer Roy Oosthuizen, whose land was located in an area firmly established as Upper Ecca (Middle Permian), collected a number of nodules containing the remains of several therapsids, including several small dicynodonts and the partial skull that is the type specimen of Eodicynodon.

[1] Below is a cladogram modified from Angielczyk and Rubidge (2010) showing the phylogenetic relationships of Dicynodontia:[7] Eodicynodon Colobodectes Lanthanostegus Robertia Diictodon Prosictodon Chelydontops Endothiodon Pristerodon Emydops Myosaurus Dicynodontoides Kombuisia Cistecephalus Cistecephaloides Kawingasaurus Interpresosaurus Elph Rhachiocephalus Oudenodon Tropidostoma Australobarbarus Odontocyclops Idelesaurus Aulacephalodon Geikia Pelanomodon Katumbia Delectosaurus Dicynodon Lystrosauridae Kannemeyeriiformes Vivaxosaurus