Kaufman (2007: 72) has also added Lule–Vilela and Zamucoan,[4] while Morris Swadesh proposed a Macro-Mapuche stock that included Matacoan, Guaicuruan, Charruan, and Mascoyan.

Campbell (1997) has argued that those hypotheses should be further investigated, though he no longer intends to evaluate it.

[5] Jolkesky (2016) notes that there are lexical similarities with the Arawakan, Tupian, Trumai, and Ofayé language families due to contact, pointing to an origin of Proto-Mataguayo-Guaicuruan in the Upper Paraguay River basin.

[6]: 439 Internal classification by Jolkesky (2016):[6] († = extinct) Campbell and Grondona (2012) consider the languages to be part of a Chaco linguistic area.

Common Chaco areal features include SVO word order and active-stative verb alignment.