The first fossils to be found in the Beaufort Group rocks that encompass the current eight biozones were discovered by Andrew Geddes Bain in 1856.

[10] After embarking on further study of dinocephalian fossils and their biostratigraphy, Boonstra defined the lower, middle, and upper sections of this biozone.

[17] The rocks of the Tapinocephalus Assemblage Zone consist mainly of maroon to greyish red or purple mudstone layers which exhibit blocky weathering at exposed outcrops.

The mudstones contain calcareous nodules and sheet limestones, both are indicative of a warm and seasonally arid climate, revealing the presence of paleocalcretes and carbonate precipitation respectively in playa lakes.

The siltstones frequently contain both symmetrical and asymmetrical ripple surfaces which indicate that paleocurrents traveled downstream in a northerly direction.

[22] As the name for this biozone suggests, it is renowned by paleontologists for its diverse Dinocephalian fossil species where almost all members of this family – the Anteosauridae, Titanosuchidae, and Tapinocephalidae – are represented.

Other notable dinocephalian species which have been discovered from this biozone are the advanced tapinocephalids Struthiocephalus whaitsi and Moschops capensis, and the unusual Styracocephalus platyrhynchus.

Parareptile species such as the pareiasaur, Bradysaurus, and the perplexing putative pantestudine Eunotosaurus africanus are confined to this biozone.

Dinocephalian fossils, along with other therapsid species found in the Tapinocephalus Assemblage Zone, have been recovered from the Rio do Rasto Formation from the Paraná Basin in Brazil[36] and from the Madumabisa Mudstone in Zambia.