Protypotherium praerutilum Ameghino, 1887b Holotype. MACN-A 1081 (Figs. 1 H���I), an incomplete skull, and MACN-A 1082 (Figs. 1 J���K), a broken mandible, both belonging to the same individual. Diagnosis (Ameghino 1887b: 15). ��� Tama��o m��s peque��o [que Protypotherium australe]. Ultima muela inferior con la separaci��n del tercer l��bulo apenas indicada. Longitud de las siete muelas inferiores, 35 mm. Alto de la rama horizontal debajo del m. 1 , 16 mm ���. English translation. Smaller size [than Protypotherium australe]. Last lower molar with the separation of the third lobe slightly marked. Length of the seven lower molars, 35 mm. Height of mandibular ramus below m 1, 16 mm. Comments. In 1889, Ameghino expanded the original description of the species by including more characteristics associated to the mandible and its lower dentition. He also featured the skull and its mandible (Ameghino 1889, plate 14: figs. 6���7) along with three isolated lower anterior teeth (i2, i3, c; figs. 8, 12���13). According to Ameghino���s catalogue, MACN-A 1081 and MACN-A 1082, skull and mandible of the same individual, are the type materials of this species. Meanwhile, no specimen is indicated as such by Mones (1986). MACN-A 1081 and MACN-A 1082 match the original Ameghino���s (1889) figures, herein reproduced (Figs. 1 L���O). In addition, MACN-A 1082 coincides with the original description as the talonid of its m3 presents shallow labial and lingual sulci, resulting in a slightly delimitated third lobe, and matches the measurements (length of p1��� m3 = 35.36 mm; height of the mandibular ramus below m1 = 16.7 mm) given by Ameghino (1887b). All of this supports the identification of the mandible as the type specimen of P. praerutilum, and given that the skull MACN- A 1081 belongs to the same individual as the mandible, both specimens constitute the holotype of the species. Unfortunately, the anterior lower teeth illustrated in the Atlas (Ameghino 1889, plate 14: figs. 8, 12���13) could not be located and they are considered to be lost. In addition, they do not belong to MACN-A 1082, because this specimen presents all of its anterior lower dentition. It is not evident that Ameghino had these teeth at hand when he described the species two years earlier and, in fact, he did not indicate them as type material in his catalogue as he did with the skull and mandible; consequently, we do not consider them as part of the type material. On the other hand, in the collection of palaeontology at the MLP, there are twelve fragmented specimens (MLP 12-1815, left mandible with broken p4 and m1, MLP 12-1818, left mandible with broken m1 and m2, MLP 12- 1819, left m3, MLP 12-1834, right M3, MLP 12-1845, left mandible with p4���m1, MLP 12-1854, left mandible with m2���3, MLP 12-1856, broken symphysis with broken anterior dentition, MLP 12-1877, left mandible with alveoli of p3���4 and m1���2, MLP 12-2031, left m1 or m2, MLP 12-2041, left maxilla with P4���M2, MLP 12-2084, right maxilla with P4���M2, and MLP 12-2085, maxillae with both P3���M2 series) labelled as paratypes of P. praerutilum. These labels were made in the 1960���s and are based on the information contained in the handwritten catalogue of the ���Old Collections���, which was elaborated in the 1930���s (M. Reguero���s pers. obs.), that is long after the collection of these specimens. Nevertheless, when comparing the information of these labels with the Old Collections catalogue, we noticed that there are many inconsistencies that make us question the veracity of the labelled data. Although there are handwritten indications concerning the type specimens of several species in this catalogue, none of the materials mentioned above is indicated as ��� paratype ���, which is in turn a modern terminology never used by Florentino Ameghino. Additionally, and in contrast to the labels, there is no handwritten information concerning the provenance and/or collector of these specimens. We also noticed that in this catalogue, MLP 12- 1854 is assigned to Protypotherium and not to P. praerutilum as it is printed on its label, and that MLP 12-2041, despite its assignation to P. praerutilum, exhibits its P4 completely molariform (e.g., protocone and hypocone equally developed), a fact that supports its exclusion from Genus Protypotherium. In addition, there is no evidence about who wrote these labels and, consequently, considered these specimens as paratypes of P. praerutilum. Due to these incongruences and to the fact that there is no original tag that could validate their status as paratypes or even confirm that these materials were collected in 1887 by C. Ameghino and later used by Florentino Ameghino to describe P. praerutilum, they are all rejected as the paratypes of the species. Chronological and geographical distribution of the type specimen. Santacrucian SALMA, Santa Cruz Province., Published as part of Fern��ndez, Mercedes, Fernicola, Juan Carlos, Cerde��o, 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, pp. 473-498 in Zootaxa 4387 (3) on pages 481-482, DOI: 10.11646/zootaxa.4387.3.4, http://zenodo.org/record/1187697, {"references":["Ameghino, F. (1887 b) Enumeracion sistematica de las especies de mamiferos fosiles coleccionados por Carlos Ameghino en los terrenos eocenos de la Patagonia austral y depositados en el Museo La Plata. Boletin del Museo de La Plata, 1, 1 - 26.","Ameghino, F. (1889) Contribucion al conocimiento de los mamiferos fosiles de la Republica Argentina. Actas de la Academia Nacional de Ciencias de Cordoba, 6, i - xxxii, 1 - 1027, atlas of 98 pls.","Mones A. (1986) Palaeovertebrata Sudamericana. Catalogo Sistematico de los Vertebrados Fosiles de America del Sur, Parte I. Preliminary List and Bibliography. Courier Forschungsinstitut Senckenberg, 82, 1 - 625."]}