Definition of Astrapotheria
:an order of extinct South American ungulates that may have diverged from primitive notoungulates in the Paleocene, flourished in the Oligocene and Miocene, and were distinguished by large size with marked disproportion between the powerful forequarters and feebly developed hindquarters, cowlike incisors accompanied by immense persistently growing canines and huge molars, and probably an elephantine proboscis
