Interatherium rodens Ameghino, 1887a

Fernández, Mercedes, Fernicola, Juan Carlos & Cerdeño, 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, Zootaxa 4543 (2), pp. 195-220 : 198-199

Interatherium rodens Ameghino, 1887a

Interatherium rodens Moreno, 1882: 117 , nomen nudum. Ameghino, 1887a: 63, ex Moreno 1882.

Holotype. MLP 12-2826 ( Fig. 1 A ), right maxilla with alveolus of dP1, dP2 and P3–M3 series.

Age and provenance of the type material. Santacrucian SALMA, early Miocene , Santa Cruz Province ( Argentina).

Original description ( Ameghino 1887a: 63). “ Talla comparable a la de una liebre. Paladar profundo, cóncavo, liso y con un pequeño agujero palatino en la sutura anterior del palatino con el maxilar. Sutura anterior del palatino con el maxilar al nivel del P4. Último molar superior implantado con su eje mayor en dirección de la serie dentaria. Apófisis cigomática del maxilar con un proceso descendiente suborbitario. Órbita del ojo, grande.

Serie dentaria superior formando un arco muy pronunciado. […] De este animal sólo se conoce el maxilar superior derecho con todas sus muelas, menos el pm. 1, recogido por Moreno durante su viaje de 1876–1877 ”.

English translation. Size similar to that of a hare. The palate is deep, concave, smooth and presents a small palatine foramen anterior to the palatine-maxilla suture. This suture is at the level of P4. The last upper molar is implanted with its major axis in the same direction as the dental series. The zygomatic process of the maxilla presents a suborbital descending process. The orbits are large. Upper dental series forms a very pronounced arch. [...] This animal is only known by a right maxilla with all its cheek teeth, except for its P1, which has been collected by Moreno during his 1876 – 1877 exploration.

Comments. Ameghino (1887a) described this species based on a right maxilla collected by Francisco P. Moreno in 1876 – 1877. The same year, Ameghino (1887b) included other characteristics regarding I2 – C and provided the length of dp1–p2–m3 series. Subsequently, Ameghino (1889: plate 15, figs. 20–26) significantly expanded his previous descriptions by studying some mandibular and cranial fragments that he also illustrated, including a maxilla herein reproduced ( Fig. 1 B ). Florentino indicated that this specimen was in fact the maxilla used by Moreno to erect I. rodens and that it was deposited in the MLP at that time.

Despite Ameghino’s acknowledgment regarding the status of the maxilla, he stated in his personal catalogue that MACN-A 377 to MACN-A 387 were the type materials of I. rodens . In contrast, Mones (1986) indicated the maxilla MLP 12-2826 as the type material of the species. This specimen is in fact the maxilla originally described and later illustrated by Ameghino (1887a, 1889) and, as a result, it is confirmed as the holotype of I. rodens . On the contrary, MACN-A 377 to MACN-A 387 are discarded as paratypes of I. rodens because, when reconstructing the history of these materials, they were given to Florentino by his brother Carlos in September of 1887, that is after the publication on the maxilla in April of 1887.

Figures

FIGURE 1. Interatherium rodens, holotype MLP 12-2826, right maxilla with alveolus of dP1 and complete dP2 and P3–M3, in occlusal view (A); reproduction of figure 26 (B) from Ameghino (1889, plate 15). Interatherium anguliferum, holotype MACN-A 3444, right maxilla with C and P2–M1, in occlusal view (C). Interatherium interruptum, holotype MACN-A 3445, left maxilla with the alveolus of dP1 and complete dP2–3 and P4–M3, in occlusal view (D). Interatherium dentatum, holotype MACN-A 9863, skull and mandible articulated, left lateral view (E). Scale bar = 10 mm.