What is "notioprogonia"

Notioprogonia is a suborder of the extinct mammalian order Notoungulata and includes two families, Henricosborniidae and Notostylopidae.

Notioprogonia includes the most primitive notoungulates and has argued that Notioprogonia is paraphyletic because it would include the ancestors of the remaining suborders. Notioprogonia is not a natural group but an assemblage of primitive notoungulates; the two families assigned here simply do not clearly belong to any other clades.