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In this contribution we present new specimens of Litopterna recovered during the last decade in Quebrada Fiera (Mendoza Province, Argentina), whose fossiliferous sediments, currently recognized as the base of Agua de la Piedra Formation, are assignable to Late Oligocene (Deseadan South American Land Mammal Age). Two remains mentioned in the first publication on this locality were neither detailed nor described, and they have not been located in the corresponding repository. The new material consists of postcranial fragmentary remains (astragali, calcaneum, and metapodials) of Macraucheniidae (Cramaucheniinae) and an incomplete upper molar (M3) of Proterotheriidae (Proterotheriinae). These few remains of litopterns contrast with the abundance of notoungulates at Quebrada Fiera. A comparative study was carried out with material from Patagonia (Argentina) and taxa recorded in Bolivia and Peru for the same temporal interval. The specimens of Cramaucheniinae are assigned to Coniopternium andinum and the molar of Proterotheriinae to cf. Lambdaconus suinus. This contribution allows us to extend the geographical range of Coniopternium, filling the gap between the Patagonian and lower latitude localities (Bolivia and Peru) in which this genus was found. The record of L. suinus in Quebrada Fiera expands the geographical range of this species outside from Patagonia. RESUMEN En este trabajo se describen nuevos ejemplares de Litopterna recuperados durante la última década en la localidad de Quebrada Fiera (Mendoza, Argentina). Los sedimentos fosilíferos, actualmente reconocidos como la base de la Formación Agua de la Piedra, son asignables al Oligoceno tardío (Edad Mamífero Deseadense). Los dos restos mencionados en la primera publicación sobre esta localidad nunca se detallaron ni describieron, y no han sido localizados en el repositorio correspondiente. El nuevo material consiste en restos poscraneanos fragmentarios (astrágalos, calcáneo y metápodos) de Macraucheniidae (Cramaucheniinae) y un molar superior incompleto (M3) de un Proterotheriidae (Proterotheriinae). Esta escasez de litopternos contrasta con la abundancia de notoungulados en Quebrada Fiera. Se realizó un estudio comparativo con materiales de la Patagonia (Argentina) y de taxones registrados en Bolivia y Perú para el mismo lapso. Los restos de Cramaucheniinae se asignan a Coniopternium andinum y el molar de Proterotheriinae a cf. Lambdaconus suinus. Esta contribución permite ampliar el rango geográfico de Coniopternium a un área intermedia entre las localidades patagónicas y de latitudes más bajas (Bolivia y Perú) en donde se ha registrado este género. Asimismo, se extiende la presencia de L. suinus fuera de Patagonia.

Icochilus senilis Ameghino, 1894a Holotype. MACN-A 3596 (Fig. 4 C), incomplete skull, MACN-A 3597 (Fig. 4 D), complete mandible, and MACN-A 3598 to MACN-A 3630, postcranial elements, all of them from the same individual. Age and provenance of the type material. Santacrucian SALMA, early Miocene, Santa Cruz Province (Argentina). Original description (Ameghino 1894a: 15). ��� Cette esp��ce est de la taille de l��� I. extensus, mais un peu plus robuste; elle se distingue facilement par la deuxi��me pr��molaire inf��rieure qui n'est pas bilob��e, mais de contour elliptique et par cons��quent sans sillon vertical, ni sur la face interne ni sur l'externe. La troisi��me et quatri��me pr��molaire inf��rieure ainsi que les vraies molaires, sont plus larges que dans les autres esp��ces. La deuxi��me pr��molaire sup��rieure est aussi de contour elliptique et sans sillon. Il y a un diast��me assez long entre la canine inf��rieure et la premi��re pr��molaire. Longueur des sept molaires inf��rieures, 32 mm ���. English translation. This species is of the size of Ic. extensus, but it is a little more robust; it is easily distinguished by the second lower premolar that is not bilobated but elliptical and, subsequently, without internal and external vertical grooves. The third and fourth lower premolars, as well as the true molars, are wider than in the other species. The second upper premolar is also elliptical and without groove. There is a rather long diastema between the lower canine and the first premolar. Length of the seven lower molars, 32 mm. Comments. Ameghino (1894a) did not illustrate any specimen of this species. According to Ameghino���s catalogue and Mones (1986), MACN-A 3596 to MACN-A 3630, an almost complete individual, constitute the type specimen of this species. The mandible MACN-A 3597 and the skull MACN-A 3596 present the respective p2 and P2 elliptical in cross section with very shallow lingual and labial grooves. In addition, the dimensions of MACN-A 3597 (length of the diastema c���dp1 = 2 mm; length of the lower tooth row = 32 mm) match those provided by Ameghino (1894a). Therefore, MACN-A 3596 to MACN-A 3630 are confirmed as the holotype of Ic. senilis., Published as part of Fern��ndez, Mercedes, Fernicola, Juan Carlos & Cerde��o, Esperanza, 2019, On the type materials of the genera Interatherium Ameghino, 1887 and Icochilus Ameghino, 1889 (Interatheriidae, Notoungulata, Mammalia) from early Miocene of the Santa Cruz Province, Argentina, pp. 195-220 in Zootaxa 4543 (2) on page 209, DOI: 10.11646/zootaxa.4543.2.2, http://zenodo.org/record/2617757, {"references":["Ameghino, F. (1894 a) Enumeration synoptique des especes de mammiferes fossiles des formations eocenes de Patagonie. Coni e hijos, Buenos Aires, 196 pp.","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."]}

Icochilus robustus Ameghino, 1891 Holotype. MACN-A 3454 (Fig. 4A) to MACN-A 3505, complete skull and mandible of the same individual, with associated postcranial elements. Age and provenance of the type material. Santacrucian SALMA, early Miocene, Santa Cruz Province (Argentina). Original description (Ameghino 1891: 393). ��� Del tama��o de Icochilus extensus, del que se distingue por el cr��neo m��s ancho y por los frontales que se prolongan adelante entre los nasales ���. English translation. Of the same size as Icochilus extensus, from which it is distinguished by presenting a wider skull and the frontals extended forward between the nasals. Comments. Ameghino (1891: 393, figs. 95���97) briefly described this species in a footnote, stating that he had the entire skeleton of an individual. He also illustrated a foot, a right hand and an almost complete skull. According to Ameghino���s catalogue and Mones (1986), MACN-A 3454 to MACN-A 3505, an almost complete individual, constitute the type specimen of the species. MACN-A 3454 is indeed the illustrated complete skull (Ameghino 1891: fig. 97), herein reproduced (Fig. 4 B), although it has suffered many breaks. Regarding the right manus and foot, only some elements (basipodia, metapodia and phalanges) are present. At the beginning of the current study, all of these materials were in different uncovered containers, so it is assumed that different elements have been missed over the years. Therefore, MACN 3454 to MACN-A 3505 are confirmed as elements of the holotype of Ic. robustus., Published as part of Fern��ndez, Mercedes, Fernicola, Juan Carlos & Cerde��o, Esperanza, 2019, On the type materials of the genera Interatherium Ameghino, 1887 and Icochilus Ameghino, 1889 (Interatheriidae, Notoungulata, Mammalia) from early Miocene of the Santa Cruz Province, Argentina, pp. 195-220 in Zootaxa 4543 (2) on page 209, DOI: 10.11646/zootaxa.4543.2.2, http://zenodo.org/record/2617757, {"references":["Ameghino, F. (1891) Nuevos restos de mamiferos fosiles descubiertos por Carlos Ameghino en el Eoceno inferior de la Patagonia austral. Especies nuevas, adiciones y correcciones. Revista Argentina de Historia Natural, 1 (5), 289 - 328.","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."]}

Interatherium brevifrons Ameghino, 1894a Holotype. Not located, probably lost. Age and provenance of the type material. Santacrucian SALMA, early Miocene, Santa Cruz Province (Argentina). Original description (Ameghino 1894a: 18). ��� Esp��ce de taille beaucoup plus petite que le I. rodens et avec toute la denture en s��rie continue, sans diast��mes. La partie ant��rieure du cr��ne est tr��s raccourcie. L'i. 1 est tr��s grande et les i. 2 et 3 tr��s petites. La canine est bien d��velopp��e. Longueur de la partie ant��rieure de l'i. 1 �� la partie post��rieure de la m 3 , 27 mm ���. English translation. Species much smaller in size than I. rodens and with all the dentition in continuous series, without diastemata. The anterior part of the skull is very short. I1 is very large and I2���3 are very small. The canine is well developed. Length from the anterior part of I1 to the posterior part of m3, 27 mm. Comments. Ameghino (1894a) did not add any illustration to the original description of the species. According to Ameghino���s catalogue, the cranial fragment MACN-A 3440 is the type specimen of I. brevifrons. Instead, Mones (1986) indicates the fragmented maxilla MACN-A 3441 as such. MACN-A 3440 does not match the original description because it does not exhibit a complete dental series and it presents two diastemata, anterior and posterior to the upper canine. Therefore, it is discarded as the type specimen of the species. On the other hand, MACN-A 3441 can neither be considered the type material, because it is a very fragmented specimen with only three molariforms (Ameghino���s catalogue indicates ��� tres muelas ��� [three cheek teeth], so there is no option of having lost any dental piece through time). Unfortunately, no material that matches the original description (Ameghino 1894a) was located within the studied collections., Published as part of Fern��ndez, Mercedes, Fernicola, Juan Carlos & Cerde��o, Esperanza, 2019, On the type materials of the genera Interatherium Ameghino, 1887 and Icochilus Ameghino, 1889 (Interatheriidae, Notoungulata, Mammalia) from early Miocene of the Santa Cruz Province, Argentina, pp. 195-220 in Zootaxa 4543 (2) on page 201, DOI: 10.11646/zootaxa.4543.2.2, http://zenodo.org/record/2617757, {"references":["Ameghino, F. (1894 a) Enumeration synoptique des especes de mammiferes fossiles des formations eocenes de Patagonie. Coni e hijos, Buenos Aires, 196 pp.","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."]}

Icochilus extensus Ameghino, 1889 Lectotype (this contribution). MACN-A 1083 (Figs. 2 A���B) and MACN-A 1084 (Figs. 2 C���D), an almost complete skull and mandible with complete dentitions, both belonging to the same individual. Paralectotypes (this contribution). Four isolated teeth, not located (see below). Age and provenance of the type material. Santacrucian SALMA, early Miocene, Santa Cruz Province (Argentina). Original description (Ameghino 1889: 471���472). ��� Esta es la especie de mayor tama��o, cuya talla era un poco superior �� la del conejo. Los premolares 2 , 3 y 4 se distinguen f��cilmente de los de las dem��s especies, por presentar sobre la parte anterior de la cara externa dos aristas estrechas separadas por una ranura angosta y profunda; de estas dos aristas, la anterior que forma el ��ngulo ��ntero-externo de cada diente es mas peque��a y mas baja, y la posterior mas ancha y considerablemente mas elevada tomando la forma de una columna perpendicular saliente. La parte posterior externa detr��s de la columna mencionada es mas baja y plana, uni��ndose �� la cara posterior formando un ��ngulo redondeado. Los verdaderos molares superiores tienen las dos aristas de la parte anterior de la cara externa mas estrechas y de tama��o mas igual, sin que la segunda tome la forma de columna perpendicular saliente. Detr��s de esta segunda ��rista viene una depresi��n perpendicular colocada sobre la mitad del ancho de la cara externa de la muela, de fondo c��ncavo pero poco profunda. Cada uno de los verdaderos molares superiores presenta sobre el borde externo de la corona dos c��spides �� cerros puntiagudos, formados por el prolongamiento de las ondulaciones convexas perpendiculares de la cara externa. En la mand��bula inferior, los dos l��bulos que forman cada muela, son de forma mas distinta entre s�� que en las otras especies; el l��bulo anterior tiene el lado interno mucho mas estrecho y en forma de arista perpendicular angosta y saliente dirijida hacia atr��s, y el lado externo mas ancho y redondeado, con su eje mayor dirijido oblicuamente de afuera hacia adentro y de adelante hacia atr��s, presentando la cara posterior de un ancho considerable; el l��bulo posterior es tambi��n igualmente muy estrecho sobre el borde interno y mas grueso sobre el externo, pero presenta su parte anterior que se une al l��bulo que lo precede considerablemente mas angosta que la posterior. La mand��bula inferior presenta tres agujeros mentonianos, el anterior mas grande, colocado debajo de la barra que separa el p. 1 del c. 1 en el punto en que la s��nfisis se comprime transversalmente para tomar la forma de pico, el segundo mucho mas peque��o est�� colocado debajo del p. 2 , y el tercero igualmente peque��o, se encuentra debajo de la parte anterior del p. 4 . La cara externa de la rama horizontal debajo de los premolares es gruesa y convexa. La rama ascendente presenta el borde anterior con la base que sale del lado externo de la ��ltima muela levant��ndose hacia arriba formando una peque��a curva c��ncava, pero su parte superior que constitu��a la ap��fisis coronoides se inclina h��cia adelante ���. English translation. This is the largest species, being a little larger in size than a rabbit. P2���4 are easily distinguishable from those of the other species, because they have two narrow edges separated from each other by a narrow and deep groove on the antero-external face; of these two edges, the anterior one, which forms the anteroexternal angle of each tooth, is smaller and lower, while the posterior is wider and considerably higher resembling a perpendicular projecting column. The postero-external region behind this column is lower and flat, joining the posterior face in a rounded angle. M1���3 also presents two antero-external edges but both are narrower and of equal size, and the posterior edge does not take the form of a perpendicular projecting column. Behind this second edge, there is a perpendicular depression, concave but shallow, placed about half the width of the external face of the molar. Each molar has two pointed cusps or hills on the external margin of the crown which are formed by the prolongation of the convex and perpendicular undulations of the external face. In the mandible, the two lobes that constitute each tooth, are more distinct from each other than in the other species; the inner side of the anterior lobe is much narrower than the external and similar to a narrow, perpendicular and protruding edge which directs backwards, whereas the external side is broader and rounded with its major axis obliquely directed, with the posterior face being considerable wide; the posterior lobe is also very narrow on the inner face and thicker on the external, but the anterior part that joins the preceding lobe is considerably narrower than the posterior lobe. The mandible has three mental foramina, the anterior is the largest and it is placed below the diastema that separates p1 from c at the point where the symphysis is transversely compressed acquiring the shape of a beak, the second is much smaller in size and it is placed below p2, and the third is equally smaller and is placed below the anterior margin of p4. Below the lower premolars, the external face of the horizontal mandibular ramus is thick and convex. The ascending ramus of the mandible presents its anterior border with the base that emerges from the external side of m3 rising upwards forming a small concave curve, but its upper part, which constitutes the coronoid process, slopes forwards. Comments. Ameghino (1889: 471���472, plate 15: figs. 4���5) described and illustrated this species based on a partial skull and mandible of the same individual, along with four isolated teeth���I1, right upper premolar, right upper molar and left lower molariform���(Ameghino 1889, plate 15: figs. 6���9). According to Ameghino���s catalogue and Mones (1986), the skull MACN-A 1083 and the mandible MACN-A 1084 are the type specimens of Ic. extensus. Following Ameghino���s catalogue, both are part of the same animal, which is confirmed by us because they articulate to each other. MACN-A 1083 and MACN-A 1084 correspond to figures 4 and 5, respectively, of the Atlas (Ameghino 1889: plate 15), and are herein reproduced (Figs. 2 E���H). The isolated teeth (Ameghino 1889: plate 15, figs. 6���9), which were not even mentioned in the written catalogue, were not located in the collection and, due to the fact that MACN-A 1083 and MACN-A 1084 already exhibit these teeth, we conclude that they do not belong to the same individual as the skull and mandible; nevertheless, these teeth would be part of the original syntypes. As the original diagnosis was based on the characteristics of the skull and mandible, we designate MACN-A 1083 plus MACN-A 1084 as the lectotype of Ic. extensus. Consequently, the remaining syntypes become paralectotypes (ICZN 2000: Art. 73.2.2)., Published as part of Fern��ndez, Mercedes, Fernicola, Juan Carlos & Cerde��o, Esperanza, 2019, On the type materials of the genera Interatherium Ameghino, 1887 and Icochilus Ameghino, 1889 (Interatheriidae, Notoungulata, Mammalia) from early Miocene of the Santa Cruz Province, Argentina, pp. 195-220 in Zootaxa 4543 (2) on pages 203-205, DOI: 10.11646/zootaxa.4543.2.2, http://zenodo.org/record/2617757, {"references":["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.","ICZN (2000) Codigo internacional de nomenclatura zoologica. 4 th edition, CSIC-MNCN Madrid, Caja Espana, The International Comission on Zoological Nomenclature and Sociedad de Amigos del MNCN (eds), Madrid, 156 pp."]}

Icochilus trilineatus Ameghino, 1894a Syntypes. MACN-A 3633 (Fig. 5 B), fragmented left maxilla with M2; and MACN-A 3651 to MACN-A 3657 (Figs. 5 C���H), isolated cheek teeth. Age and provenance of the type material. Santacrucian SALMA, early Miocene, Santa Cruz Province (Argentina). Original description (Ameghino 1894a: 16). ��� Cette esp��ce est de la m��me taille que l��� I. extensus, dont elle se distingue facilement aussi bien que des autres esp��ces, par la forme de ses molaires et pr��molaires sup��rieures. Chacune de ces dents porte sur sa face externe un sillon large et profond qui la divise en deux lobules, et sur chaque lobule il y a un sillon ��troit et profond qui le divise en deux colonnettes verticales; on voit ainsi sur la face externe de chaque dent, quatre colonnettes s��par��es par trois sillons, dont celui du milieu beaucoup plus large et les autres deux tr��s ��troits ���. English translation. This species has the same size as Ic. extensus, from which it is easily distinguished, as well as from the other species, by the morphology of its upper molars and premolars. Each tooth presents a broad and deep groove on its external face, which divides it into two lobules, and on each lobule there is a narrow and deep groove that divides it into two vertical columns; as a result, the external face of each tooth exhibits four columns separated by three grooves, the second being the widest whereas the other two are very narrow. Comments. Ameghino (1894a) did not illustrate this species. According to Ameghino���s catalogue and Mones (1986), MACN-A 3633, a small maxillary fragment with M2, is the type specimen of the species. The ectoloph of this M2 exhibits three perpendicular grooves, one in the middle and one at each lateral lobe, resulting in an ectoloph with four columns as indicated by Ameghino (1894a). Nonetheless, when describing the species, Ameghino (1894a: 16) alluded to the form of its upper molars and premolars, which implies that he had more than one tooth at hand, and therefore MACN-A 3633 cannot be the only type specimen. In this context, in the Ameghino Collection, the lot MACN-A 3651 to MACN-A 3657 contains six isolated teeth (instead of seven as corresponding inventory numbers), five of which (two M3, and three upper molariforms, probably P4 and/or M1/2) show the characteristics mentioned by Ameghino (1894a); thus, we consider them as part of the type series. As the specimens in the lot lack individual labels, it is not possible to identify which is the missing seventh tooth. Therefore, MACN-A 3633 and MACN-A 3651 to MACN-A 3657 (one currently missing) are considered the syntypes of Ic. trilineatus., Published as part of Fern��ndez, Mercedes, Fernicola, Juan Carlos & Cerde��o, Esperanza, 2019, On the type materials of the genera Interatherium Ameghino, 1887 and Icochilus Ameghino, 1889 (Interatheriidae, Notoungulata, Mammalia) from early Miocene of the Santa Cruz Province, Argentina, pp. 195-220 in Zootaxa 4543 (2) on page 211, DOI: 10.11646/zootaxa.4543.2.2, http://zenodo.org/record/2617757, {"references":["Ameghino, F. (1894 a) Enumeration synoptique des especes de mammiferes fossiles des formations eocenes de Patagonie. Coni e hijos, Buenos Aires, 196 pp.","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."]}

Interatherium interruptum Ameghino, 1894a Holotype. MACN-A 3445 (Fig. 1 D), left maxilla with the alveolus of dP1, and series dP2���3 and P4���M3. Age and provenance of the type material. Santacrucian SALMA, early Miocene, Santa Cruz Province (Argentina). Original description (Ameghino 1894a: 18). ��� De la taille de 1��� I. supernum. Cette esp��ce se distingue facilement par la pr��sence de la premi��re pr��molaire sup��rieure qui est plac��e contre la partie ant��rieure de la deuxi��me, et par la disparition compl��te de la canine. Il y a une longue barre qui s��pare la premi��re pr��molaire de l'incisive externe; le bord de cette barre porte un sillon longitudinal profond qui suit la m��me direction de la s��rie dentaire. Longueur des sept molaires sup��rieures, 25 mm ���. English translation. With the same size as I. supernum. This species is easily distinguished by the presence of the first upper premolar that is placed against the anterior part of the second, and by the complete absence of the upper canine. There is a long diastema that separates the first premolar from the external incisor; the margin of this diastema shows a deep longitudinal groove that has the same direction as the dental series. Length of the seven upper molars, 25 mm. Comments. Ameghino (1894a) did not illustrate this species. According to Ameghino���s catalogue and Mones (1986), the left maxilla MACN-A 3445 is the type specimen of the species. This material lacks the canine and, instead, exhibits a long diastema placed anteriorly to the alveolus of dP1 (L = 4.1 mm). It also shows the groove described by Ameghino, and the length of dP1���M3 is 24.8 mm. All of this coincides with Ameghino���s (1894a) description and, consequently, MACN-A 3445 is confirmed as the holotype of I. interruptum., Published as part of Fern��ndez, Mercedes, Fernicola, Juan Carlos & Cerde��o, Esperanza, 2019, On the type materials of the genera Interatherium Ameghino, 1887 and Icochilus Ameghino, 1889 (Interatheriidae, Notoungulata, Mammalia) from early Miocene of the Santa Cruz Province, Argentina, pp. 195-220 in Zootaxa 4543 (2) on page 202, DOI: 10.11646/zootaxa.4543.2.2, http://zenodo.org/record/2617757, {"references":["Ameghino, F. (1894 a) Enumeration synoptique des especes de mammiferes fossiles des formations eocenes de Patagonie. Coni e hijos, Buenos Aires, 196 pp.","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."]}

Interatherium dentatum Ameghino, 1894a Holotype. MACN-A 9863 (Fig. 1 E), anterior cranial fragment and an almost complete mandible in anatomical connection. Age and provenance of the type material. Santacrucian SALMA, early Miocene, Santa Cruz Province (Argentina). Original description (Ameghino 1894a: 18). ��� Par la taille se rapproche de 1��� I. supernum; il s'en distingue pour poss��der une pr��molaire de plus �� la m��choire sup��rieure, c'est-��-dire cinq au lieu de quatre. Les deux premi��res pr��molaires sont coniques, la premi��re ou ant��rieure ��tant s��par��e de la deuxi��me. La s��rie dentaire sup��rieure compl��te occupe un espace de 41 mm ���. English translation. It is close to I. supernum by its size; it differs from it in having an additional premolar in the maxilla, which means five instead of four. The first two premolars are conical, the first (or anterior) being separated from the second. The complete upper dental series occupies a space of 41 mm. Comments. Ameghino (1894a) did not add any illustration to the original description. No specimen is indicated as the type material of I. dentatum in Ameghino���s catalogue, and Mones (1986) wrote ���MACN?���, which means doubts or lack of information regarding the type that could be housed at the MACN. There are three specimens assigned to I. dentatum within the Ameghino Collection: the articulated skull and mandible MACN-A 9863, and two fragmented maxillae, MACN-A 9864 and MACN-A 9865, corresponding to two different individuals. These maxillae lack its anterior portion, so the region that should contain the extra premolar is not preserved in any of them; as the areas of breakage are not recent, both specimens are discarded as the type. Instead, MACN-A 9863 matches the original description (Ameghino 1894a) as it presents an extra alveolus between C and dP1, which is separated from the latter by a distinct diastema. The length of left I1 ���M3 series (41.3 mm) also matches the only measurement provided by Ameghino (1894a). Consequently, MACN-A 9863 is considered the holotype of I. dentatum., Published as part of Fern��ndez, Mercedes, Fernicola, Juan Carlos & Cerde��o, Esperanza, 2019, On the type materials of the genera Interatherium Ameghino, 1887 and Icochilus Ameghino, 1889 (Interatheriidae, Notoungulata, Mammalia) from early Miocene of the Santa Cruz Province, Argentina, pp. 195-220 in Zootaxa 4543 (2) on page 202, DOI: 10.11646/zootaxa.4543.2.2, http://zenodo.org/record/2617757, {"references":["Ameghino, F. (1894 a) Enumeration synoptique des especes de mammiferes fossiles des formations eocenes de Patagonie. Coni e hijos, Buenos Aires, 196 pp.","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."]}

Icochilus curtus Ameghino, 1894a Holotype. Not located, probably lost. Age and provenance of the type material. Santacrucian SALMA, early Miocene, Santa Cruz Province (Argentina). Original description (Ameghino 1894a: 17). ��� De la m��me taille que l��� I. extensus. Cette esp��ce se distingue facilement par le grand raccourcissement de la derni��re molaire inf��rieure qui est �� peine un peu plus longue que l'avant-derni��re, et par son lobe post��rieur qui est convexe sur le c��t�� externe, sans vestige du sillon perpendiculaire qu'on voit sur la m��me dent des autres esp��ces. La derni��re molaire inf��rieure a pr��s de 5 mm. de longueur, et les deux derni��res molaires occupent un espace de 9 mm. de long ���. English translation. With the same size as Ic. extensus. This species is easily distinguished by the great shortening of the last lower molar, which is just a little longer than m2, and by its posterior lobe that is convex on the external side and it does not exhibit the perpendicular groove seen on the same tooth in the other species. The last lower molar is nearly 5 mm long, and the last two molars occupy a space of 9 mm. Comments. Ameghino (1894a) did not illustrate this species. According to Ameghino���s catalogue and Mones (1986), the mandibular fragment MACN-A 9852 is the type material of the species. However, MACN-A 9852 does not match the original description, because its m3 exhibits a labial groove in the talonid as in other species of Icochilus. Among the remaining specimens assigned to this species within the Ameghino Collection, other two fragmented mandibles, MACN-A 9853 and MACN-A 9854, neither present the diagnostic characteristics described for the m3. In addition, no material labelled as Icochilus sp., Interatherium sp., Icochilini, Icochilinae and Interatheriidae indet. matches the original description provided by Ameghino (1894a). As a result, the type specimen of Ic. curtus has not been located., Published as part of Fern��ndez, Mercedes, Fernicola, Juan Carlos & Cerde��o, Esperanza, 2019, On the type materials of the genera Interatherium Ameghino, 1887 and Icochilus Ameghino, 1889 (Interatheriidae, Notoungulata, Mammalia) from early Miocene of the Santa Cruz Province, Argentina, pp. 195-220 in Zootaxa 4543 (2) on page 215, DOI: 10.11646/zootaxa.4543.2.2, http://zenodo.org/record/2617757, {"references":["Ameghino, F. (1894 a) Enumeration synoptique des especes de mammiferes fossiles des formations eocenes de Patagonie. Coni e hijos, Buenos Aires, 196 pp.","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."]}

Protypotherium globosum Ameghino, 1891 Holotype. MACN-A 4049 (Figs. 2 M���N), an almost complete skull lacking the left premaxilla. Diagnosis (Ameghino 1891: 292). ��� Tama��o bastante m��s peque��o que el Protypotherium australe (Moreno) Ameghino. Se distingue por los parietales, que se levantan bastante m��s arriba que los frontales, de superficie globosa, cortos y que atr��s descienden hacia abajo de una manera casi repentina. Frente muy ancha y plana; nasales cortos. Longitud del cr��neo, 8 cent��metros. Di��metro transverso m��ximo, 53 mil��metros. Di��metro interorbitario de los frontales, 3 cent��metros. Longitud de la serie dentaria superior, 45 mil��metros ���. English translation. Considerably smaller size than Protypotherium australe (Moreno) Ameghino. It can be distinguished by its short parietals that rise much higher than the frontals, with a globular surface, and suddenly descend downwards posteriorly. Forehead very broad and flat; nasals short. Length of the skull, 8 centimetres. Maximum transverse diameter, 53 millimetres. Interorbital diameter of the frontals, 3 centimetres. Length of upper tooth row, 45 millimetres. Comments. Ameghino (1891) described this taxon without any illustration. According to Ameghino���s catalogue and to Mones (1986), the incomplete skull MACN-A 4049 is the type material of the species. This specimen matches the original diagnosis (Ameghino 1891) both in morphology (e.g., the most posterior region of the frontals and the anterior portion of the parietals form a convex surface that rapidly descends posteriorly, frontals are wide and flat, and nasals and parietals are short) and measurements (length of the skull = 84.2 mm; maximum transverse diameter = 53.4 mm; interorbital frontal diameter = 30.1 mm; length of the upper tooth row = 45 mm), and it is herein confirmed as the holotype of P. globosum. 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 page 485, DOI: 10.11646/zootaxa.4387.3.4, http://zenodo.org/record/1187697, {"references":["Ameghino, F. (1891) Nuevos restos de mamiferos fosiles descubiertos por Carlos Ameghino en el Eoceno inferior de la Patagonia austral. Especies nuevas, adiciones y correcciones. Revista Argentina de Historia Natural, 1 (5), 289 - 328.","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."]}

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."]}

Protypotherium Ameghino, 1885 Protypotherium Ameghino 1882: 39, nomen nudum. Ameghino, 1885: 81 ���83. Type species. Protypotherium antiquum Ameghino 1882: 39, nomen nudum. Ameghino, 1885: 81���83., 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 page 476, DOI: 10.11646/zootaxa.4387.3.4, http://zenodo.org/record/1187697, {"references":["Ameghino, F. (1885) Nuevos restos de mamiferos fosiles oligocenos, recogidos por el profesor Pedro Scalabrini y pertenecientes al Museo Provincial de la Ciudad del Parana. Boletin de la Academia Nacional de Ciencias de Cordoba, 8, 5 - 207.","Ameghino, F. (1882) Catalogo explicativo de las colecciones de Antropologia prehistorica y de paleontologia de Florentino Ameghino, Partido de Mercedes. In: Urioste, C., Ambrosetti, T., Butteler, B., de Toledo, R. A., Ruiz, F., Lainez, M., Schroder, E., Quesada, H., Duggan, M. & Araujo Munoz, R. C. (Eds.), Catalogo de la Seccion de la provincia de Buenos Aires (Republica Argentina), en la Exposicion Continental Sudamericana. Anexo A, Buenos Aires, pp. 35 - 42."]}

Protypotherium australe (Ameghino, 1887a) Holotype. Left maxilla with P3–M3; original piece has not been found, but there are two casts in the MACN: MACN-A 1338 (Fig. 1 G) and MACN-A 1345–46. Diagnosis (Ameghino 1887a: 63). “ Talla comparable a la del Dolichotis patachonica. Corona de los molares superiores fuertemente excavada. Paladar poco profundo y relativamente plano. Lóbulo anterior de los verdaderos molares superiores un poco más ancho que el posterior. […] De este animal sólo se conoce el maxilar superior izquierdo, con las cinco últimas muelas más o menos rotas, excepto las dos últimas, que están enteras. Ha sido encontrado, como el precedente, por F. P. Moreno, durante su viaje de 1876–1877 ”. English translation. Size similar to that of Dolichotis patachonica. Crown of upper cheek teeth strongly excavated. Palate shallow and relatively flat. Anterior lobe of upper molars slightly wider than the posterior one. [...] This animal is only known from the left upper jaw, with the last five cheek teeth more or less broken, except for the last two that are complete. It has been found, like the precedent, by F. P. Moreno, during his 1876 – 1877 exploration. Comments. In the original diagnosis, Ameghino (1887a) highlighted that the maxilla collected by Moreno was the only known material of P. australe. Shortly after, Ameghino (1887b) completed the former diagnosis by giving the dimensions of a mandibular fragment with at least p1–m3. Once again, Ameghino (1889, plate 14: figs. 9–11, 14–18) expanded the original description of the species and illustrated three isolated upper teeth (I1, P2 and M1; figs. 9–11), three isolated lower teeth (p3, p4 and m1; figs. 14–16), a right maxillary fragment with P4–M3 (fig. 17), and a left mandibular ramus with its teeth (fig. 18). It is worth to mention that he recognised that by 1889 this species was known only by fragmentary materials and that there was no complete upper or lower series available. None of these illustrated specimens is the left maxilla used in the original description as they involve isolated teeth, a mandibular fragment and a right maxilla, which leads us to conclude that the holotype was not illustrated. According to Ameghino’s catalogue, MACN-A 3882, an incomplete skull with almost complete dentition (alveoli of both I1 and left I2–3, and complete right I2 –M3 and left C–M3), and MACN-A 3884, a mandibular symphysis and its right mandibular ramus, are the type specimens. In contrast, Mones (1986) did not indicate any type specimen, and just mentioned “ MLP (-)”, meaning that it was supposed to be housed at the MLP but that it could also be lost. MACN-A 3882 is discarded as the holotype because it does not correspond to the fragmented left maxilla initially described by Ameghino (1887a). In turn, MACN-A 3884 is the mandibular fragment described shortly after (Ameghino 1887b), but it is not part of the type material as this is only composed of one specimen as highlighted by Ameghino (1887a), which is the maxillary fragment that constitutes the holotype. In contrast, there are two identical casts in the Ameghino Collection, MACN-A 1338 and MACN-A 1345–46, which match the original diagnosis as they are the casts of a left maxilla with broken P3, labially incomplete P4–M1 and complete M2–3, strongly excavated tooth row, and M1–3 with anterior lobe slightly wider than the posterior lobe. In addition, Ameghino wrote “Moreno” next to the description of MACN-A 1338 in his catalogue, and “tipo de Toxodontophanus Mo. ” next to MACN-A 1345–46, a fact that reinforces the inference that they correspond to the maxilla collected by Moreno and, therefore, both are recognised as casts of the holotype. Unfortunately, the original piece has not been located, as no specimen in the studied collections—by direct observations (e.g., MACN, MLP and ZMK) and/or by means of photographs (e.g., AMNH, FM and YPM)— matches the original description of P. australe and the casts MACN-A 1338 and MACN-A 1345–46. Chronological and geographical distribution of the type specimen. Santacrucian SALMA, Santa Cruz Province., Published as part of 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, pp. 473-498 in Zootaxa 4387 (3) on pages 480-481, DOI: 10.11646/zootaxa.4387.3.4, http://zenodo.org/record/1187697, {"references":["Ameghino, F. (1887 a) Observaciones generales sobre el orden de mamiferos extinguidos sub-americanos llamados Toxodontes (Toxodontia) y sinopsis de los generos y especies hasta ahora conocidos. Anales del Museo de La Plata, 1 (1), 1 - 66.","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."]}

Patriarchus altus Ameghino, 1891 Holotype. MACN-A 4001 (Figs. 4 C���D), almost complete skull. Paratype. MACN-A 3999, incomplete skull, and MACN-A 4000, incomplete mandible, both of the same individual. Diagnosis (Ameghino 1891: 293). ��� Igual conformaci��n general que la especie precedente [Patriarchus leptocephalus], pero de tama��o mucho mayor; rostro m��s elevado y paladar un poco m��s ancho adelante. Longitud del cr��neo, 102 mil��metros; longitud de la serie dentaria superior, 59 mil��metros; ancho interorbital de los frontales, 28 mil��metros; longitud de los frontales, 30 mil��metros. Los frontales no penetran adelante entre los nasales ���. English translation. Same general configuration as the preceding species [Patriarchus leptocephalus], but much larger; higher rostrum and palate a little wider anteriorly. Length of the skull, 102 millimetres; length of upper tooth row, 59 millimetres; interorbital width of the frontals, 28 millimetres; length of the frontals, 30 millimetres. Frontals do not penetrate forward between the nasals. Comments. Ameghino (1891) described this species, but did not add any figure of it. According to Ameghino���s catalogue, the skull MACN-A 4001 is the type of this species, whereas the cranial fragment MACN-A 3999 and its mandibular portion MACN-A 4000 are indicated each as ��� tipo 2�� ��� (2nd type), meaning that they are paratypes. Mones (1986) also indicated MACN-A 3999 to MACN-A 4001 as the type specimens of Pa. altus, but did not distinguish between type and 2nd type. The skull MACN-A 4001 matches the original diagnosis as it is larger (length of C���M3 = 45.05 mm) than the holotype of Pa. leptocephalus (length of C���M3 = 37.35 mm), its rostrum is more elevated and the anterior region of the palate is wider. All the measurements (skull length = 103.25 mm; length of the upper tooth row = 58.55 mm; interorbital width of the frontals = 29.26 mm; length of the frontals = 33 mm) also match those provided by Ameghino (1891). As a result, we confirm MACN-A 4001 as the holotype of Pa. altus. In the case of the individual MACN-A 3999 plus MACN-A 4000, it is also confirmed as the paratype because, despite the fact that MACN-A 3999 is not complete enough to take any of the given measurements, none of these specimens contradicts the diagnosis and both were recognised by Ameghino as ��� tipo 2�� ��� when he acknowledged the type specimen. In summary, we confirm MACN-A 4001 as the holotype of Pa. leptocephalus and the individual MACN-A 3999 plus MACN-A 4000 as the paratype 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 page 493, DOI: 10.11646/zootaxa.4387.3.4, http://zenodo.org/record/1187697, {"references":["Ameghino, F. (1891) Nuevos restos de mamiferos fosiles descubiertos por Carlos Ameghino en el Eoceno inferior de la Patagonia austral. Especies nuevas, adiciones y correcciones. Revista Argentina de Historia Natural, 1 (5), 289 - 328.","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."]}

Protypotherium lineare Ameghino, 1894a Holotype. MACN-A 4038 (Fig. 2 S), right mandibular fragment with alveolus of p1, and p2���m1, and MACN-A 4039 (Fig. 2 T), left mandibular fragment with p3���m2 series, both specimens of the same individual. Diagnosis (Ameghino 1894a: 13���14). ��� Cette esp��ce, par la taille se rapproche du P. australe, mais s'en distingue facilement par les deux derni��res pr��molaires inf��rieures qui, au lieu d'��tre implant��es obliquement comme dans les autres esp��ces, sont plac��es avec leur grand axe dans la m��me direction de la s��rie dentaire. A cons��quence de cette disposition, le sillon vertical, au lieu d'��tre plac�� en arri��re il est en dehors; ce sillon est tr��s profond, et le lobule post��rieur externe de chaque pr��molaire est bien d��velopp��, formant une colonne ��troite mais ��lev��e. Longueur des sept molaires inf��rieures 38 mm. Hauteur de la mandibule: en dessous de la 2 p. 13 mm.; en dessous de la partie ant��rieure de l�� 3 m. 20 mm ���. English translation. This species is close in size to Protypotherium australe, but it is easily distinguished from it by the last two lower premolars that, instead of being obliquely implanted as in the other species, are placed with their major axis in the same direction of the tooth row. Due to this position, the vertical groove is placed outside instead of backwards; this groove is very deep, and the posterior lobe of each premolar is externally well developed, forming a narrow and high column. Length of the seven lower teeth: 38 mm. Height of the mandible: below p2, 13 mm; below the anterior region of m3, 20 mm. Comments. Ameghino (1894a) did not add any illustration to the description of P. lineare. In the Ameghino Collection, this species is represented by eight materials. According to Ameghino���s catalogue and to Mones (1986), two mandibular fragments, MACN-A 4038 and MACN-A 4039, are the type material of the species; following Ameghino���s catalogue, both belong to the same individual. Due to the presence of recent breaks, it is inferred that m3 got lost. Nevertheless, the measurements available to be taken (height of the mandibular ramus below p2 = 13.7 mm; below the mesial region the alveolus of left m3 = 19.8 mm) match those provided by Ameghino (1894a). Regarding the remaining six specimens assigned to P. lineare, five of them are too incomplete mandibular fragments, smaller than MACN-A 4038 and MACN-A 4039, and those with their p2 and/or m3 do not match the original measurements regarding the height of the mandible; then, they are all discarded as type specimens. The sixth specimen, MACN-A 4040 (partial right mandible with c, alveoli of p1���3 and complete p4���m3), is closer in size to the original mandibular fragment, but it is still smaller (height of the mandibular ramus below p2 = 12.48 mm; below m3 = 17.36 mm), and lacks its p3 (the alveolus is filled with sediment), which also allows discarding it as the type specimen because Ameghino specifically described p3���4. Consequently, the individual MACN-A 4038 plus MACN-A 4039 is confirmed as the holotype of P. lineare. 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 486-487, DOI: 10.11646/zootaxa.4387.3.4, http://zenodo.org/record/1187697, {"references":["Ameghino, F. (1894 a) Enumeration synoptique des especes de mammiferes fossiles des formations eocenes de Patagonie. Coni e hijos, Buenos Aires, 196 pp.","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."]}

Patriarchus rectus Ameghino, 1891 Holotype. MACN-A 4005 (Fig. 3 N), right maxilla with alveolus of C and series P1���M3; MACN-A 4006 (Fig. 3 O), left maxillary fragment with series M1���3; and MACN-A 4007 (Fig. 3 P), mandibular fragment with incomplete symphysis, broken alveoli of left and right i1-2 and complete left series i3 ���m3, all of them of the same individual. Diagnosis (Ameghino 1891: 293). ��� De tama��o una mitad menor que las especies precedentes [Patriarchus furculosus y Patriarchus distortus] y de series dentarias superiores casi rectas, P3 a M2 mucho m��s prolongados en el lado interno. Incisivos intermedios inferiores m��s aplastados de arriba abajo. Longitud de la serie dentaria inferior, 43 mil��metros. Ancho interorbitario de los frontales, 24 mil��metros ���. English translation. One half smaller than the preceding species [Patriarchus furculosus and Patriarchus distortus], with upper tooth rows almost straight, P3 to M2 much longer on the internal side. Lower median incisors more flattened. Length of the lower tooth row, 43 mm. Interorbital width of the frontals, 24 mm. Comments. Ameghino (1891) erected this species but did not illustrate any specimens of it. According to Ameghino���s catalogue and to Mones (1986), the maxillary fragments MACN-A 4005 and MACN-A 4006, and the fragmented mandible MACN-A 4007, all of the same individual, are the type materials of this species. These specimens match the original diagnosis as they are smaller (length of P1���M3 = 30.5 mm; length of P2���M3 = 27.5 mm; length of p2���m3 = 29.23 mm) than the type material of Pa. furculosus (length of P2���M3 = 36.5 mm; length of p2���m3 = 41.05 mm) and Pa. distortus (length of P1���M3 = 37.3 mm), and the incomplete palate (MACN-A 4005 plus MACN-A 4006) exhibits almost straight upper tooth rows. It is noteworthy that there is no evidence of the frontals in MACN-A 4005 and MACN-A 4006, so it was not possible to measure the interorbital width of these elements. Additionally, the length occupied by the left lower tooth row (~ 41 mm) of MACN-A 4007 differs from the value provided by Ameghino (1891), but this is due to the breakage of the mandibular incisor area. Nevertheless, MACN-A 4005 to MACN-A 4007 are confirmed as the holotype of Pa. rectus. 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 page 491, DOI: 10.11646/zootaxa.4387.3.4, http://zenodo.org/record/1187697, {"references":["Ameghino, F. (1891) Nuevos restos de mamiferos fosiles descubiertos por Carlos Ameghino en el Eoceno inferior de la Patagonia austral. Especies nuevas, adiciones y correcciones. Revista Argentina de Historia Natural, 1 (5), 289 - 328.","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."]}

Protypotherium convexidens Ameghino, 1891 Holotype. MACN-A 4054 (Fig. 2 O), right maxilla with P3���M2 (broken). Diagnosis (Ameghino 1891: 292). ��� De tama��o un poco menor que Protypotherium australe (Moreno) Ameghino , del cual se distingue f��cilmente 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 mil��metros ���. 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., 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 page 485, DOI: 10.11646/zootaxa.4387.3.4, http://zenodo.org/record/1187697, {"references":["Ameghino, F. (1891) Nuevos restos de mamiferos fosiles descubiertos por Carlos Ameghino en el Eoceno inferior de la Patagonia austral. Especies nuevas, adiciones y correcciones. Revista Argentina de Historia Natural, 1 (5), 289 - 328.","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."]}

Patriarchus diastematus Ameghino, 1891 Holotype. MACN-A 4044 (Fig. 3 Q), two maxillae with alveoli of left and right C���P1, right P2���M3 and left P2��� M2. Diagnosis (Ameghino 1891: 293). ��� Del mismo tama��o que la especie precedente [Patriarchus rectus], o apenas algo mayor, de la cual se distingue por el P1 peque��o, cil��ndrico y separado del que sigue por un peque��o diastema. Series dentarias superiores un poco m��s arqueadas. Longitud del P2 al M3, 29 mil��metros. Ancho del paladar entre los M3, 18 mil��metros; ancho entre los M1, 20,5 mil��metros; ancho entre los P2, 13 mil��metros ���. English translation. Same size as the preceding species [Patriarchus rectus] or slightly larger, from which it is distinguished by its small, cylindrical P1, separated from the following premolar by a small diastema. Upper tooth row a little more arched. Length from P2 to M3, 29 millimetres. Width of the palate between M3s, 18 millimetres; between M1s, 20.5 millimetres; between P2s, 13 millimetres. Comments. Ameghino (1889) described this species without providing any illustration of it. In the Ameghino Collection, Pa. diastematus is represented just by one specimen. According to Ameghino���s catalogue and to Mones (1986), maxilla MACN-A 4044 is the type material. This specimen matches the original description because it presents a slightly larger size (length of P2���M3 = 28.1 mm) to that of the holotype of Pa. rectus (length of P2���M3 = 27.5 mm) and, according to its alveolus, P1 is small and cylindrical and is separated from P2 by a small diastema (~ 1.4 mm). Besides, all the measurements (length of P2���M3 = 28.88 mm; width of the palate between both M3 = 19 mm; width of the palate between both M1 = 20.8 mm; width of the palate between both P2 = 13.7 mm) coincide with those provided by Ameghino (1891). As a result, MACN-A 4044 is confirmed as the holotype of Pa. diastematus. 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 page 492, DOI: 10.11646/zootaxa.4387.3.4, http://zenodo.org/record/1187697, {"references":["Ameghino, F. (1891) Nuevos restos de mamiferos fosiles descubiertos por Carlos Ameghino en el Eoceno inferior de la Patagonia austral. Especies nuevas, adiciones y correcciones. Revista Argentina de Historia Natural, 1 (5), 289 - 328.","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."]}