Megatheriinae is a subfamily of the Megatheriidae, an extinct family of ground sloths that lived from the Middle Miocene to the Early Holocene.

These still possessed a caniniform anterior tooth, which was separated from the posterior molar-like teeth by a small diastema .

The more derived Megatheriinae, which are known from the Middle Miocene to the Early Holocene, on the other hand, had fully homodontic molars in a closed row.

[5] Based on skull studies, the Nothrotheriidae, in which, among other genera, Nothrotherium, Nothrotheriops, and the semiaquatic Thalassocnus are placed, are regarded as a separate family, which forms the sister group of the Megatheriidae.

[6] Prepoplanops Planops Prepotherium Diabolotherium Megathericulus Anisodontherium Pyramiodontherium Proeremotherium Eremotherium Megatherium