of the Roadian, or possibly even the Kungurian epoch, but no trace has been found. These animals radiated at the expense of the dying pelycosaurs, who dominated during the early part of the Permian and may have even gone extinct due to competition with therapsids, especially the short-lived but most dominant dinocephalians. Even the earliest members, the estemmenosuchids and early brithopodids of the Russian Ocher fauna, were already a diverse group of herbivores and carnivores. During the Wordian and early Capitanian, advanced dinocephalians radiated into a large number of herbivorous forms, representing a diverse megafauna. This is well known from the Tapinocephalus Assemblage Zone of the Southern African Karoo. At the height of their diversity (middle or late Capitanian age) all the dinocephalians suddenly died out, during the Capitanian mass extinction event. The reason for their extinction is not clear; although disease, sudden climatic change, or other factors of environmental stress may have brought about their end. They were replaced by much smaller therapsids; herbivorous Dicynodontia and carnivorous Biarmosuchians, Gorgonopsians and Therocephalians. Taxonomy Class Synapsida Order Therapsida Suborder Dinocephalia ?Driveria ?Eccasaurus ?Mastersonia ?Pelosuchus ?Tappenosaurus Family Estemmenosuchidae Estemmenosuchus Molybdopygus ?Parabradysaurus ?Family Phreatosuchidae Phreatosaurus Phreatosuchus ?Family Phthinosuchidae Phthinosuchus ?Family Rhopalodontidae ?Phthinosaurus Rhopalodon Clade Anteosauria Family Anteosauridae Family Brithopodidae Family Deuterosauridae Clade Tapinocephalia ?Dimacrodon Family ?Driveriidae Family ?Mastersoniidae Family Styracocephalidae Family Tapinocephalidae Family Titanosuchidae See also Evolution of mammals List of Permian tetrapods References Further reading Carroll, R. L. (1988), Vertebrate Paleontology and Evolution, WH Freeman & Co. External links Dinocephalia at Palaeos Dinocephalia at Palaeocritti Taxa named by Harry Seeley Guadalupian first appearances Guadalupian extinctions