''Megistotherium'' ("greatest beast") is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of hyainailourid

hyaenodonts Hyaenodontidae ("hyena teeth") is a family of extinct predatory mammals from extinct superfamily Hyaenodontoidea within extinct order Hyaenodonta. Hyaenodontids arose during the early Eocene and persisted well into the early Miocene. Fossils of t ...

from paraphyletic subfamily

Hyainailourinae Hyainailourinae (" hyena- cats") is an extinct paraphyletic subfamily of hyainailourid hyaenodonts that lived in Africa, Asia, North America and Europe during the middle Eocene to middle Miocene. Classification and phylogeny Taxonomy * Subfa ...

that lived in

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

Etymology

The name of this genus comes and . The name of species ''Megistotherium osteothlastes'' comes and (with ''-es'' being an agent noun: 'bone-crusher').

Description

''Megistotherium osteothlastes'' is the only known

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

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

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 ...

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

Kenya ) , national_anthem = " Ee Mungu Nguvu Yetu"() , image_map = , map_caption = , image_map2 = , capital = Nairobi , coordinates = , largest_city = Nairobi ...

Egypt Egypt ( ar, مصر , ), officially the Arab Republic of Egypt, is a transcontinental country spanning the northeast corner of Africa and southwest corner of Asia via a land bridge formed by the Sinai Peninsula. It is bordered by the Medit ...

,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.

Namibia Namibia (, ), officially the Republic of Namibia, is a country in Southern Africa. Its western border is the Atlantic Ocean. It shares land borders with Zambia and Angola to the north, Botswana to the east and South Africa to the south and ea ...

Uganda }), is a landlocked country in East Africa. The country 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 south by Tanzania. The sou ...

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 (; ar, ليبيا, Lībiyā), officially the State of Libya ( ar, دولة ليبيا, Dawlat Lībiyā), is a country in the Maghreb region in North Africa. It is bordered by the Mediterranean Sea to the north, Egypt to the east, Suda ...

. 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

shear Shear may refer to: Textile production *Animal shearing, the collection of wool from various species **Sheep shearing *The removal of nap during wool cloth production Science and technology Engineering *Shear strength (soil), the shear strength ...

ing action.

Paleoecology

The land that is now the

Sahara desert , photo = Sahara real color.jpg , photo_caption = The Sahara taken by Apollo 17 astronauts, 1972 , map = , map_image = , location = , country = , country1 = , ...

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 scavengers of large African herbivores. Gomphothere bones have been found with its fossils, indicating that ''Megistotherium'' may have hunted them for food.

Classification and phylogeny

Taxonomic history

The family Hyainailouridae comprised a diverse group of hyaenodont predators that were most successful during the

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

before being possibly ecologically displaced by the order Carnivora during the late Oligocene. ''Megistotherium'' emerged in the

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

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a subcontinent of Eurasia and it is located entirel ...

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an are ...

and

,J. Morales, M. Pickford, S. Fraile, M. J. Salesa and D. Soria (2003.) "Creodonta and Carnivora from Arrisdrift, early Middle Miocene of southern Namibia" Mem. Geol. Surv. Namibia 19 177–194. and therefore comes from the same localities.

Phylogeny

The phylogenetic relationships of genus ''Megistotherium'' are shown in the following cladogram:

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