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 Author Fernández, Mercedes Author Fernicola, Juan Carlos Author Cerdeño, Esperanza text Zootaxa 2019 2019-01-07 4543 2 195 220 journal article 27706 10.11646/zootaxa.4543.2.2 7438332f-a925-43aa-b17f-059781bdfc12 1175-5326 2617757 11F546CD-109F-4CBC-B87D-EA8D1AD0B96F Icochilus truncus Ameghino, 1894a Holotype . MACN-A 3635 ( Figs. 5 J–K), right fragmented mandible with alveoli of i1 –dp1 and the series p2–m1. Age and provenance of the type material. Santacrucian SALMA, early Miocene , Santa Cruz Province ( Argentina ). Original description ( Ameghino 1894a: 16 ). “ A peu près de la même taille que l’ I. extensus . Elle se distingue par la présence de la première prémolaire inférieure très petite, et par l'absence de la canine inférieure. A la place de la canine il y a un diastème assez étendu qui sépare l'incisive externe de la première prémolaire ”. English translation. Size almost the same as Ic. extensus . It is distinguished by the presence of a very small first lower premolar, and by the absence of the lower canine. In the place of the lower canine there is a rather extensive diastema that separates the external incisor from the first premolar. Comments. Ameghino (1894a) did not add any illustration to the brief description of I. truncus . According to Ameghino’s catalogue and Mones (1986) , MACN-A 3635, a broken symphysis with a fragmented right mandibular ramus, is the type material of the species. This specimen has a small alveolus of dp1 and a diastema between i3 and dp1, whose length ( 2.2 mm ) falls within the range ( 1 to 3 mm ) that Ameghino provided for any gap between adjacent teeth ( Ameghino 1894a: 15–18 ). These characteristics are consistent with Ameghino’s (1894a) description and, consequently, MACN-A 3635 is confirmed as the holotype of Ic. truncus .