''Interatherium'' is an extinct genus of interatheriid mammal from the Early to Middle Miocene (

Colhuehuapian The Colhuehuapian age is a period of geologic time (21.0–17.5 Ma) within the Early Miocene epoch of the Neogene, used more specifically within the SALMA classification in South America. It follows the Deseadan and precedes the Santacrucian ag ...

- Mayoan). Fossils have been found in the Santa Cruz, Collón Curá and

Sarmiento Formation The Sarmiento Formation (Spanish: ''Formación Sarmiento''), in older literature described as the Casamayor Formation, is a geological formation in Chubut Province, Argentina, in central Patagonia, which spans around 30 million years from the mid- ...

s in Argentina.''Interatherium''
at

Fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals ...

.org

Description

This animal, of the size similar to that of today's American Mink (it was about 40 centimeters long excluding the tail), was equipped with a rather unusual morphology if related to that of its closest relatives. Contrary to shapes like ''

Protypotherium ''Protypotherium'' is an extinct genus of notoungulate mammals native to South America during the Oligocene and Miocene epochs. A number of closely related animals date back further, to the Eocene. Fossils of ''Protypotherium'' have been found in ...

,'' ''Interatherium'' possessed short and robust legs, and a long body and similar to that of a weasel. The front legs were equipped with four fingers. The ointment phalanges were compressed laterally, and some of these were divided. The ''Interatherium'' skull was equally aberrant: it was in fact much more compact than that of other archaic types, and the muzzle was as if it had been crushed. The jaw, in particular, was very deep and tall, protruded backwards and owned considerable notches for the insertion of powerful masses masses (one of the main muscles capable of chewing in mammals). The Masseter muscle was anchored to a large bony flange placed in the lower part of the jaw, known as the descending process. This process is greatly reduced in related interatheres: ''Interatherium'''s well developed process was superficially similar to the ones seen in

glyptodont Glyptodonts are an extinct subfamily of large, heavily armoured armadillos. They arose in South America around 48 million years ago and spread to southern North America after the continents became connected several million years ago. The best-kn ...

s, a taxon of giant armadillos. Like the other interactors, ''Interatherium'' possessed a complete teeth, including 44 teeth, but differ in having a diastema between the incisors and premolars. The space was accentuated by the dimensions of the last incisive and the canine, so small as to be absent in some specimens.Fernández, M., Fernicola, J. C., & Cerdeño Serrano, M. E. (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.
/ref>Fernández, M. (2015). Revisión taxonómica de ''Interatherium'' Ameghino 1887 e ''Icochilus'' Ameghino 1889 (Interatheriidae, Notoungulata) de la Edad Mamífero Santacrucense (Mioceno Temprano) de la Provincia de Santa Cruz, Argentina. ''Luján: Departamento de Ciencias Básicas, Universidad Nacional de Luján''.

Classification

''Interatherium'' was described for the first time in 1887 by Florentino Ameghino, on the basis of fossil remains found in the province of Santa Cruz, Argentina, in strata dating to the lower Miocene. The type species is ''Interatherium rodens'', which was named on the basis of a right maxilla that was first collected by Francisco P. Moreno in 1876-77. Several other species were described by Ameghino in 1894 (''I. anguliferum, I. brevifrons, I. dentatum, I. interruptum, I. rodens, I. supernum, I. excavatus''), many of which were then considered synonyms of ''I. rodens,'' though many of their holotypes have been lost. ''Interatherium'' is the eponymous genus of the

Interatheriidae Interatheriidae is an extinct family of notoungulate mammals from South America. Interatheriids are known from the Middle Eocene (Mustersan) to the Early Pliocene (Montehermosan).McKenna & Bell, 1997Linares, 2004 These animals were principally sm ...

family, a family that includes numerous medium-sized species from the Miocene of South America; ''Interatherium'' was most closely related to another Interathere from Santa Cruz, ''

Cochilius ''Cochilius'' is an extinct genus of interatheriid notoungulate that lived between the Late Oligocene and the lower Miocene in what is now Argentina. Description The skull and skeleton show features also found in other similar contemporary o ...

.''

Paleobiology

Due to the short legs and the elongated body, some paleontologists believe that ''Interatherium'' may have been an animal that lived in hypogean dens, but the legs do not show particular adaptations in this sense. It was certainly a herbivorous animal that fed on leaves, grass and vegetation that grew at the ground level, perhaps close to bodies of water.Kramarz, A. G., Vucetich, M. G., Carlini, A. A., Ciancio, M. R., Alejandra, M., Abello, C. M. D., & Gelfo, J. N. (2010). 18 A new mammal fauna at the top of the Gran Barranca sequence and its biochronological significance. ''The paleontology of Gran Barranca: evolution and environmental change through the middle Cenozoic of Patagonia'', 264.

References

Typotheres Miocene mammals of South America Mayoan Laventan Colloncuran Friasian Santacrucian Colhuehuapian Neogene Argentina Fossils of Argentina Fossil taxa described in 1887 Taxa named by Florentino Ameghino Prehistoric placental genera Austral or Magallanes Basin Golfo San Jorge Basin Santa Cruz Formation Sarmiento Formation {{paleo-mammal-stub