''Megistotherium'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of hyaenodont belonging to the family

Hyainailouridae Hyainailouridae ("hyena-like Felidae, cats") is a Paraphyly, paraphyletic family of extinct predatory mammals within the Polyphyly, polyphyletic superfamily Hyaenodonta, Hyainailouroidea within extinct order Hyaenodonta. Hyainailourids arose duri ...

that lived in

Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

and possibly

Asia Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...

as well. It first appeared in

Early Miocene The Early Miocene (also known as Lower Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages: the Aquitanian age, Aquitanian and Burdigalian stages. The sub-epoch lasted from 23.03 ± 0.05 annum, Ma to ...

to late

Middle Miocene The Middle Miocene is a sub-epoch of the Miocene epoch (geology), epoch made up of two Stage (stratigraphy), stages: the Langhian and Serravallian stages. The Middle Miocene is preceded by the Early Miocene. The sub-epoch lasted from 15.97 ± 0. ...

from 22.5 to 12.0 million years ago, existing for .

Taxonomy

The name of this genus comes and . The name of species ''Megistotherium osteothlastes'' comes and (with ''-es'' being an agent noun: 'bone-crusher'). The family Hyainailouridae comprised a diverse group of hyaenodont predators that were most successful during the

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

before being possibly ecologically displaced by the order

Carnivora Carnivora ( ) is an order of placental mammals specialized primarily in eating flesh, whose members are formally referred to as carnivorans. The order Carnivora is the sixth largest order of mammals, comprising at least 279 species. Carnivor ...

during the late

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

. ''Megistotherium'' emerged in the

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

towards the end of the hyaenodonts' 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 In taxonomy, the scientific classification of living organisms, a synonym is an alternative scientific name for the accepted scientific name of a taxon. The botanical and zoological codes of nomenclature treat the concept of synonymy differently. ...

of ''Hyainailouros sulzeri'', which is known by an almost complete skeleton, among other remains, and has been found in

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

and

Namibia Namibia, officially the Republic of Namibia, is a country on the west coast of Southern Africa. Its borders include the Atlantic Ocean to the west, Angola and Zambia to the north, Botswana to the east and South Africa to the south; in the no ...

, and therefore comes from the same localities.

Description

''Megistotherium osteothlastes'' is the only known

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

from this genus, and it was a large hyainailourid that lived during the Early and Middle

. Its remains have been found in the Ngorora and Muruyur Formations of

Kenya Kenya, officially the Republic of Kenya, is a country located in East Africa. With an estimated population of more than 52.4 million as of mid-2024, Kenya is the 27th-most-populous country in the world and the 7th most populous in Africa. ...

Egypt Egypt ( , ), officially the Arab Republic of Egypt, is a country spanning the Northeast Africa, northeast corner of Africa and Western Asia, southwest corner of Asia via the Sinai Peninsula. It is bordered by the Mediterranean Sea to northe ...

,Morlo, M., Miller, E.R., and El-Barkooky, A.N. 2007. Creodonta and Carnivora from Wadi Moghra, Egypt. Journal of Vertebrate Paleontology 27: 145–159.

Uganda Uganda, officially the Republic of Uganda, is a landlocked country in East Africa. It is bordered to the east by Kenya, to the north by South Sudan, to the west by the Democratic Republic of the Congo, to the south-west by Rwanda, and to the ...

Morales, J. and M. Pickford. (2008). "Creodonts and carnivores from the Middle Miocene Muruyur Formation at Kipsaraman and Cheparawa, Baringo District, Kenya." ''Comptes Rendus Palevol'' 7 (8): 487-497 and

Libya Libya, officially the State of Libya, is a country in the Maghreb region of North Africa. It borders the Mediterranean Sea to the north, Egypt to Egypt–Libya border, the east, Sudan to Libya–Sudan border, the southeast, Chad to Chad–L ...

. Named by Robert Savage in 1973, ''Megistotherium'' is one of the largest known hyaenodonts. Like the other hyaenodonts, it had an enormous skull relative to its body; up to in length and a body mass estimated at . The

carnassial Carnassials are paired upper and lower teeth modified in such a way as to allow enlarged and often self-sharpening edges to pass by each other in a shearing manner. This adaptation is found in carnivorans, where the carnassials are the modified f ...

teeth of ''Megistotherium'' (like those of other hyaenodonts) were the upper first molars, and overlapped with their lower molar counterparts like scissors to form a formidable and powerful shearing action.

Paleoecology

The land that is now the

Sahara desert The Sahara (, ) is a desert spanning across North Africa. With an area of , it is the largest hot desert in the world and the list of deserts by area, third-largest desert overall, smaller only than the deserts of Antarctica and the northern Ar ...

was much more fertile in the Miocene. A considerable amount of it was grassland and rainfall was plentiful. Lakes and ponds provided water for large fauna, which provided ''Megistotherium'' and other predators with an ample supply of prey. Large hyaenodontids like this one could have originally evolved as specialized predators or

scavenger Scavengers are animals that consume Corpse decomposition, dead organisms that have died from causes other than predation or have been killed by other predators. While scavenging generally refers to carnivores feeding on carrion, it is also a he ...

s of large African herbivores.

Gomphothere Gomphotheres are an extinct group of proboscideans related to modern elephants. First appearing in Africa during the Oligocene, they dispersed into Eurasia and North America during the Miocene and arrived in South America during the Pleistocene a ...

bones have been found with its fossils, indicating that ''Megistotherium'' may have hunted them for food. The extinction of ''Megistotherium'' and other Hyainailouroidea was thought to correlate with increasing aridity in Africa, as they were more adapted for forested environments. The youngest known remains were found in the Ngorora Formation and dated to the late Middle Miocene around 12.5 to 12 ma.

References

* Domning, D. P. (1978.) "Sirenia." Evolution of African Mammals. pp. 573–581. * Egi, Naoko (2001.) "Body Mass Estimates in Extinct Mammals from Limb Bone Dimensions: the Case of North American Hyaenodontids." Palaeontology. Vol. 44, Issue 3, Page 497. * Leakey, L. S. B. and R. J. G. Savage (Editors) (1976.) "Fossil Vertebrates of Africa." Academic Press Inc., U.S. . {{Taxonbar, from=Q1175482 Hyaenodonts Miocene mammals of Africa Fossil taxa described in 1973 Prehistoric placental genera