The subfamily is distinguished by the formula
- 4 1 4 3
- ———,
- 4 1 3 3
pm. 4 not being enlarged, and the lower molars being turberculo-sectorial. In the Deseado formation this group is only represented by a single species, based on a single tooth found by Ameghino.
Pseudhalmarhiphus guaraniticus Ameghino
P. guaraniticus Amegh., 1903, Anal. Mus. Nac. Buenos Aires, ser. 3, t. 2, p. 83.
Based on a single tooth, similar to those found in the Santa Cruz.
Abderitinae
The subfamily is distinguished by the formula
- ? ? ? ?
- ———,
- 4 1 2 3
the fourth premolar being enlarged into a sectorial tooth on the sides of which are vertical striae. The molars are buno-lophodont. The Deseado has yielded only a tiny form, designated Parabderites, which differs from the Santa Cruz genus Abderites in pm. 4, the same shape, but with few to no striae on its sides.