Identification of type materials of the species of Protypotherium Ameghino, 1885 and Patriarchus Ameghino, 1889 (Notoungulata: Interatheriidae) erected by Florentino Ameghino Author Fernández, Mercedes Author Fernicola, Juan Carlos Author Cerdeño, Esperanza Author Reguero, Marcelo A. text Zootaxa 2018 2018-02-28 4387 3 473 498 journal article 30626 10.11646/zootaxa.4387.3.4 43de8956-0706-4f8d-b5a9-f51c30c276d8 1175-5326 1187697 B53A6B20-5386-4E5A-A00F-A559EDF640DF 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 .