Also in 1990, Bonaparte merged the family Gondwanatheriidae into Sudamericidae and, together with David Krause, redefined Gondwanatheria as a multituberculate suborder that included both Ferugliotheriidae and Sudamericidae, thus rejecting a relationship between gondwanatheres and xenarthrans. Krause, Bonaparte, and Zofia Kielan-Jaworowska redescribed "Ferugliotherium" in 1992 and suggested that the teeth that "Vucetichia" was based on may have been worn specimens of "Ferugliotherium". They placed "Ferugliotherium" among multituberculates and suggested that it may be part of the suborder Plagiaulacoidea. The following year, Krause confirmed that "Vucetichia gracilis" is a synonym of "Ferugliotherium windhauseni". Together with Bonaparte, he also proposed to classify gondwanatheres as a superfamily (Gondwanatherioidea) within Plagiaulacoidea, including the families Ferugliotheriidae and Sudamericidae. In 1996, Kielan-Jaworowska and Bonaparte tentatively identified a lower jaw fragment with a multituberculate-like fourth lower premolar (p4) from Los Alamitos as "Ferugliotherium". On the basis of the morphological features of the jaw fragment, they argued that gondwanatheres are not closely related to any other multituberculate group, and consequently placed them in a suborder of their own, Gondwanatheria.