Interatheriidae
Interatheriidae is an extinct family of notoungulate mammals from South America. Interatheriids are known from the Middle Eocene to the Early Pleistocene. These animals were principally small-sized, occupying a habitat like hares, marmots and viscachas. The majority were very small, like rodents.
Interatheriidae is one of the mammal groups that best represent the fauna from the Santa [Cruz Formation, Argentina|Santa Cruz Formation]. Particularly Protypotherium with three species is characteristic of the formation: P. australe, P. praerutilum and P. attenuatum. Another well-known genus is Interatherium, particularly well represented by I. robustum.