An artist's (Alphynix) illustration of Megistotherium osteothlastes
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Hyaenodonta
Family: Hyainailouridae
Genus: Megistotherium
Type species
Megistotherium osteothlastes
Savage, 1973
Referred species
  • Megistotherium osteothlastes

Megistotherium is a hyainailourid creodont from Eocene Kenya, Egypt, Namibia, Uganda, and Libya. It is the largest hyaenodont known today, with an estimated weight of 1.3 tons. It was also one of the last creodonts to survive to the Miocene before going extinct.


M. osteothlastes was a large hyaenodontid that lived during the early Miocene epoch some 23 million years ago. Its remains have been found in the Ngorora and Muruyur Formations of Kenya, Egypt, Namibia, Uganda and Libya. Named by Robert Savage in 1973, Megistotherium is one of the largest hyaenodontids known. Like the other hyaenodontids, it had an enormous skull relative to its body; up to 66 cm (2 ft 2 in) in length and a body mass estimated at 500 kg (1,100 lb).


The clade Hyaenodontidae comprised a diverse group of creodont predators that were most successful during the Eocene before being possibly ecologically displaced by the order Carnivora during the late Oligocene. 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. Hyainailouros sulzeri is very closely related to Megistotherium, extremely similar in size, structure and ratios - with a long tail, short limbs and robust body. Other authorities have suggested that Megistotherium is actually a junior synonym of Hyainailouros sulzeri, which is known by an almost complete skeleton, among other remains, and has been found in Europe, Asia and Namibia, and therefore comes from the same localities.

In popular culture[]

  • Megistotherium appears in Jurassic Park Builder and Jurassic World The Game.