What is "typotheria"

Typotheria is a suborder of the extinct mammalian order Notoungulata and includes five families: Archaeopithecidae, Campanorcidae, Interatheriidae, Mesotheriidae, and Oldfieldthomasiidae. Cifelli indicated that Typotheria would be paraphyletic if it excluded members of the suborder Hegetotheria and he advocated inclusion of the hegetothere families Archaeohyracidae and Hegetotheriidae in Typotheria.