Four putative first lower molariforms (mf1s) of "Ferugliotherium" are known, and the only known tooth of "Trapalcotherium" is also thought to be an mf1. "Ferugliotherium" mf1s are roughly rectangular, with rounded corners, and bear two longitudinal rows of cusps. There are four cusps in the lingual row (on the side of the tongue) and three in the labial row (the side of the lips). The cusps are connected to cusps in the other row by transverse ridges and separated from cusps in their own rows by three transverse furrows. Two heavily worn "Ferugliotherium" mf1s were originally identified as upper molars of "Vucetichia gracilis" by Bonaparte in 1990. One of the two preserves the roots; at the front and back, there were two roots, fused at their bases. The mf1 of "Trapalcotherium" differs only in some details; among others, the cusps are less distinct from the crests. The sole mf2 of "Ferugliotherium" is the holotype. It bears two rows of two cusps. The cusps in the front and back pairs are connected by a broad ridge and the two pairs are separated by a deep furrow. Transverse ridges between the cusps similar to those seen in ferugliotheriids are not known in any multituberculate. On the other hand, overall patterns of cusps and ridges are essentially similar among "Ferugliotherium", "Gondwanatherium", and "Sudamerica", indicating that the three are closely related.