''Simbakubwa'' ("great

lion The lion (''Panthera leo'') is a large Felidae, cat of the genus ''Panthera'', native to Sub-Saharan Africa and India. It has a muscular, broad-chested body (biology), body; a short, rounded head; round ears; and a dark, hairy tuft at the ...

") 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 ...

hyaenodonts Hyaenodontidae ("hyena teeth") is a family of placental mammals in the extinct superfamily Hyaenodontoidea. Hyaenodontids arose during the early Eocene and persisted well into the early Miocene. Fossils of this group have been found in Asia, Nor ...

to the family

Hyainailourinae Hyainailourinae ("hyena-like Felidae, cats") is a Paraphyly, paraphyletic subfamily of Hyaenodonta, hyaenodonts from extinct paraphyletic family Hyainailouridae. They arose during the Bartonian, Middle Eocene in Africa, and persisted well into th ...

that lived in

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. ...

during the

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 ...

Discovery and Etymology

The fossils of ''Simbakubwa'' were first discovered by rural Kenyans at Meswa Bridge, Western Kenya. Thereafter, Matthew Borths and Nancy Stevens published the findings after examining the fossils which had been stored at the Nairobi National Museum in Kenya for decades. The type specimen consists of a mandible from the lower jaw, a right upper maxilla and some postcranial remains. The light wear patterns on the dentition indicate that the holotype specimen was a young adult at the time of its death. The name of this genus comes from the

Swahili language Swahili, also known as as it is referred to endonym and exonym, in the Swahili language, is a Bantu languages, Bantu language originally spoken by the Swahili people, who are found primarily in Tanzania, Kenya, and Mozambique (along the East Af ...

, meaning "great

". The species name ''Simbakubwa kutokaafrika'' means "great lion of

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 ...

”.

Description

Different regression models produce a wide range of body mass estimates for ''Simbakubwa kutokaafrika'': from a low estimate of , based on an equation derived from the m3 length of various large carnivorans, comparable to the largest lions, to an upper estimate possibly reaching up to , based on equations derived from carnassial length of hyaenodonts and m3 length of felids respectively, which would surpass the modern

polar bear The polar bear (''Ursus maritimus'') is a large bear native to the Arctic and nearby areas. It is closely related to the brown bear, and the two species can Hybrid (biology), interbreed. The polar bear is the largest extant species of bear ...

in size. However, hyainailourids possessed proportionally very large heads in comparison to their body, and postcranial remains indicate that the similar sized ''

Hyainailouros ''Hyainailouros'' ("hyena-cat") is an extinct polyphyletic genus of hyaenodont belonging to the family Hyainailouridae that lived during the Early to Late Miocene, of which there were at least three species spread across Eurasia and Africa ...

'' was about the size of a tiger, whereas the larger '' Megistotherium'' has been estimated to have reached a maximum weight of , though this study estimated the body mass of '' Megistotherium'' with a low estimate of to higher estimates of using the same methods. The study of the postcranial remains indicates ''Simbakubwa'' was possessed of a semi-digitigrade walking stance.

Paleobiology

''Simbakubwa'', like other hyainailourids, probably was a specialist hunter and

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 ...

that preyed on creatures such as

rhinoceroses A rhinoceros ( ; ; ; : rhinoceros or rhinoceroses), commonly abbreviated to rhino, is a member of any of the five extant taxon, extant species (or numerous extinct species) of odd-toed ungulates (perissodactyls) in the family (biology), famil ...

and early

proboscideans Proboscidea (; , ) is a taxonomic order of afrotherian mammals containing one living family (Elephantidae) and several extinct families. First described by J. Illiger in 1811, it encompasses the elephants and their close relatives. Three liv ...

. It may have been somewhat less specialized in crushing bone than its later relatives such as ''

''. However, like ''Hyainailouros'', ''Simbakubwa'' possessed lingually rotating

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 ...

blades, ensuring a constant shearing edge throughout its life.

References

{{Taxonbar, from1=Q63203949, from2=Q63203734 Hyaenodonts Fossil taxa described in 2019 Miocene mammals of Africa Monotypic prehistoric placental genera