[1] The holotype of Homunculus patagonicus (MACN-A 634), a partial skull, was discovered around the Río Gallegos, though more specific details of its provenance have never been given.

[1] In the same year as Florentino Ameghino's paper, Swiss geologist and palaeontologist Alcides Mercerat described an incomplete mandibular fragment, bearing part of a molar.

[2] In the paper describing H. patagonicus, Florentino Ameghino also named Anthropops perfectus, which he distinguished based on purported characteristics of the mandible and lower canine, and Pitheculus australis.

[7] However, subsequent authors, like Osvaldo A. Reig, disagreed with this assessment,[8] and 1981, Philip Hershkovitz determined that it belonged to Homunculus.

Notable among these is MACN-A 5968, the left side of a partial skull, recovered from Puesto Estancia La Costa.

[12] H. patagonicus was a robustly built, quadrupedal primate, with body mass estimates varying between 1.4 and 5.9 kg (3.1 and 13.0 lb) based on different techniques.

[13] The interorbital region, the portion of the skull between the orbits (eye sockets) was wide, similar to in titi monkeys (Callicebinae).