Protypotherium compressidens Ameghino, 1891

Fernández, Mercedes, Fernicola, Juan Carlos, Cerdeño, Esperanza & Reguero, Marcelo A., 2018, Identification of type materials of the species of Protypotherium Ameghino, 1885 and Patriarchus Ameghino, 1889 (Notoungulata: Interatheriidae) erected by Florentino Ameghino, Zootaxa 4387 (3), pp. 473-498 : 486

Protypotherium compressidens Ameghino, 1891

Holotype. MACN-A 4029 ( Fig. 2 Q ), left maxillary fragment with P3–M3, and MACN-A 4030 ( Fig. 2 R ), left mandibular fragment with p4 (talonid)–m3, of the same individual.

Diagnosis ( Ameghino 1891: 292). “ Tamaño casi igual a Protypotherium australe , pero con las muelas comprimidas lateralmente y mucho más angostas. Verdaderos molares superiores de cara externa suavemente ondulada. Longitud del p.3 al m.3, 28 milímetros. Ancho máximo de los verdaderos molares superiores, 3 milímetros ”.

English translation. Almost equal size to Protypotherium australe , but with laterally compressed and much narrower teeth. Upper molars with slightly undulated external face. Length from P3 to M3, 28 millimetres. Maximum width of true upper molars, 3 millimetres.

Comments. Ameghino (1891) did not add any illustration to his description. According to Ameghino’s catalogue and to Mones (1986), MACN-A 4029 and MACN-A 4030, fragmented maxilla and mandible, respectively, are the type specimens of the species; following Ameghino’s catalogue, both belong to the same individual, a fact that was corroborated by us since they articulate. These specimens are the only available materials assigned to P. compressidens , and both match the original diagnosis ( Ameghino 1891) because the upper and lower teeth are strongly labio-lingually compressed. Besides, the length of P3–M3 of MACN-A 4029 is 28.6 mm, and the maximum width of the upper molars (M1 being the widest) is 3.4 mm, which are similar values to those provided by Ameghino (1891). Therefore, we confirm that the individual MACN-A 4029 plus MACN-A 4030 constitute the holotype of P. compressidens .

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

Figures

FIGURE 2. Protypotherium attenuatum, syntype MACN-A 524, left maxilla with P2–M3 but lacking P1, in occlusal view (A); syntype MACN-A 628, right fragmented mandible with alveoli of i1–3 and c (broken)–m1 but lacking m2–3, in labial (B) and occlusal (C) views; reproductions of figures 21 (D), 20 (E) and 20a (F) from Ameghino (1889, plate 14). Protypotherium obstructum, holotype MACN-A 1677, lower premolar in labial, oclusal and lingual views (G); reproduction of figure 19 (H) from Ameghino (1889, plate 15). Protypotherium claudum, holotype MACN-A 551, right mandibular fragment with alveolus of p2 andp3–m2, in labial (I) and occlusal (J)views; reproductions of figures 22 (K) and 22a (L) from Ameghino (1889, plate 14). Protypotherium globosum, holotype MACN-A 4049, skull, in ventral (M) and dorsal (N) views. Protypotherium convexidens, holotype MACN-A 4054, right maxillary fragment with P3–M2 (broken), in occlusal view (O). Protypotherium diversidens, holotype MACN-A 4052, right maxillary fragment with alveolus of P1 and P2–M3, in occlusal view (P). Protypotheriumcompressidens, holotype MACN-A 4029, left maxillaryfragment withP3–M3, in occlusal view (Q); holotype MACN-A 4030, left mandibular fragment with p4 (talonid)–m3, in occlusal view (R). Protypotherium lineare, holotype MACN-A4039, right mandibular fragment with alveolus of p1 and p2–m1, in occlusal view (S); holotype MACN-A 4038, left mandibular fragment with p3–m2, in occlusal view (T). Scale bar = 10 mm.