Protypotherium convexidens Ameghino, 1891

Holotype. MACN-A 4054 (Fig. 2 O), right maxilla with P3–M2 (broken).

Diagnosis (Ameghino 1891: 292). “ De tamaño un poco menor que Protypotherium australe (Moreno) Ameghino, del cual se distingue fácilmente por sus molares superiores de cara externa ligeramente ondulada y convexa en su conjunto. Longitud del espacio ocupado por los p.3 a m.2, 19 milímetros ”.

English translation. Slightly smaller than Protypotherium australe (Moreno) Ameghino, from which it is easily distinguished by the external face of upper molars softly undulated and convex as a whole. Length occupied by P3 to M2, 19 millimetres.

Comments. Ameghino (1891) described this taxon without any illustration. According to Ameghino’s catalogue and to Mones (1986), the maxillary fragment MACN-A 4050 is the type of the species. However, MACN-A 4050 does not match the specimen originally described, because it is a maxillary fragment with P4–M1, with no evidence of recent breaks; in consequence, the specimen MACN-A 4050 cannot be considered as the holotype of the species. Instead, the specimen MACN-A 4054, a maxilla with P3–M1 and broken M2, matches the measurement (length of P3–M2 = 18.9 mm) and the original description provided by Ameghino (1891), because it is smaller than the holotype of P. australe (length of P3–M2 = 32 mm) and presents upper molars slightly labially undulated. Therefore, MACN-A 4054 is herein considered as the holotype of P. convexidens .

Chronological and geographical distribution of the type specimen. Santacrucian SALMA, Santa Cruz Province.