Megistotherium emerged in the Miocene towards the end of the hyaenodontids' flourishing; it was a part of a radiation of African hyaenodontids that occurred at that time.
Megistotherium apareceu no Mioceno contra o final do florecemento dos creodontes; foi parte dunha radiación de hienodóntidos africanos que se produciu nesta época.