''Amphimachairodus'' 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 large

machairodonts Machairodontinae is an extinct subfamily of carnivoran mammals of the family Felidae (true cats). They were found in Asia, Africa, North America, South America, and Europe from the Miocene to the Pleistocene, living from about 16 million until ...

. It is also a member of the tribe

Homotherini Homotherini is an extinct tribe (or subtribe) of carnivoran mammals of the family Felidae (true cats). The tribe is commonly known as scimitar-toothed cats. These saber-toothed cats were distributed en North America, Europe, Asia, Africa, and So ...

within Machairodontinae and is most closely related to such species as ''

Xenosmilus ''Xenosmilus hodsonae'' (from Greek, , ''xenos'', "strange" + , ''smilē'', " chisel" ) is an extinct species of the Machairodontinae, or saber-toothed cats. Description The species name ''hodsonae'' originates from Debra Hodson, the wife of ...

'', ''Homotherium'' itself, and ''

Nimravides ''Nimravides'' is a genus of extinct saber-toothed cats that lived in North America during the Late Miocene, between 10.3 and 5.332 Ma. Despite its scientific name, ''Nimravides'' does not belong to the Nimravidae, but is a true cat, belonging ...

''. It inhabited

Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago ...

Northern Africa North Africa, or Northern Africa is a region encompassing the northern portion of the African continent. There is no singularly accepted scope for the region, and it is sometimes defined as stretching from the Atlantic shores of Mauritania in t ...

and North America during the late Miocene

epoch In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided by ...

Description

There was marked sexual dimorphism in ''A. giganteus'', with males being much larger than females. The species ''Amphimachairodus coloradensis'', from the United States (formerly ''

Machairodus ''Machairodus'' (from el, μαχαίρα , 'knife' and el, ὀδούς 'tooth') is a genus of large machairodontine saber-toothed cats that lived in Africa, Eurasia and North America during the late Miocene. It is the animal from which the su ...

coloradensis'') was a significantly large animal, about at the shoulder, according to skeletal and life reconstructions, potentially making it one of the largest known felids. All ''Amphimachairodus'' species have a developed

mandibular In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movabl ...

flange, however, ''A. colaradensis'' is distinguishable from ''A. giganteus'' and ''A. kurteni'' by subtle differences in the shape of the mandible and placement of lower

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 ...

s. In size and proportions, the

Eurasian Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern Hemisphere, Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Ja ...

species ''A. giganteus'' was remarkably similar to a modern lion or

tiger The tiger (''Panthera tigris'') is the largest living cat species and a member of the genus ''Panthera''. It is most recognisable for its dark vertical stripes on orange fur with a white underside. An apex predator, it primarily preys on ...

and had a shoulder height of . This species has a skull length of around . The

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 ...

n species ''A. kabir'' (formerly ''

kabir'', from Arabic ''kabir'' = "big") is suggested to have weighed over . This would make it comparable in size to ''

'', '' Machairodus horribillis'' and slightly smaller than ''

Smilodon populator ''Smilodon'' is a genus of the extinct machairodont subfamily of the felids. It is one of the most famous prehistoric mammals and the best known saber-toothed cat. Although commonly known as the saber-toothed tiger, it was not closely related ...

''. In 2022, this species was proposed to be reassigned to a separate genus, called ''Adeilosmilus''. ''Amphimachairodus'' was about long and probably hunted as an ambush predator. Its legs were too short to sustain a long chase, but it most likely was a good jumper. It probably used its canines to cut open the throat of its prey, severing the major arteries and possibly crushing the windpipe. Its teeth were rooted to its mouth and were not as delicate as those of most other saber-toothed cats of the time, which had extremely long canines that hung out of their mouths. The fangs of ''Amphimachairodus'', however, were able to easily fit in its mouth comfortably while being long enough to be effective for hunting. ''Amphimachairodus'' also possessed a longer tail than most other large machairodont genera.

Skull

This specimen was from a large male ''A. giganteus'' with the skull measuring from the Late Miocene in China, comparable to a male lion or tiger. Deformation of the skull through natural fossilization processes has changed the shape slightly, making it asymmetrical, but overall it remains an excellent specimen for studying the cranial morphology of this particular genus and species. For felines, this skull is rather long, but rivaled by the

skulls The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...

of the two largest species of extant cats: the lion and

. When compared with the skull of a regular lion, it is long and very narrow, particularly in the muzzle and width of the

zygomatic arch In anatomy, the zygomatic arch, or cheek bone, is a part of the skull formed by the zygomatic process of the temporal bone (a bone extending forward from the side of the skull, over the opening of the ear) and the temporal process of the zygo ...

es. Its sagittal crest is well pronounced. Compared with other machairodonts, the canines are stout and capable of large amounts of stress. This characteristic is slightly remodeled in females, whose canines are slimmer and generally longer. Compared with females, the

orbit In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as ...

of males are smaller, muzzles larger, the anterior-most portion of the nasal bones generally flare upwards slightly, and the downward slope of the dorsal edge of the skull in front of the orbit is not as pronounced, producing a straighter profile. Compared with the most well known machairodont ''

Smilodon ''Smilodon'' is a genus of the extinct machairodont subfamily of the felids. It is one of the most famous prehistoric mammals and the best known saber-toothed cat. Although commonly known as the saber-toothed tiger, it was not closely rela ...

'', commonly referred to as the "saber-toothed cat", the canines are much shorter, the facial portion again is much longer, and the teeth not reduced so far in number. Several machairodonts, namely ''

Megantereon ''Megantereon'' was a genus of prehistoric machairodontine saber-toothed cat that lived in North America, Eurasia, and Africa. It may have been the ancestor of ''Smilodon''. Taxonomy Fossil fragments have been found in Africa, Eurasia, and No ...

'', bear flanges on the mandible, which are very reduced in ''A. giganteus'' though characteristics of the mandible associated with the flanges are present, particularly the lateral flattening of the anterior portion of the mandible, creating a cross section more square than semi-circular. The

dental formula Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. That is, the number, type, and morpho-physiolog ...

for this specimen is .

Paleoecology

''Amphimachairodus'' was an inhabitant of woodlands and open floodplains as based on finds in

Pikermi Pikermi ( el, Πικέρμι) is a suburb of Athens and a former community of East Attica regional unit, Greece. Since the 2011 local government reform it is part of the municipality Rafina-Pikermi, of which it is a municipal unit. The municipal ...

in Greece and

Shanxi Province Shanxi (; ; formerly romanised as Shansi) is a landlocked province of the People's Republic of China and is part of the North China region. The capital and largest city of the province is Taiyuan, while its next most populated prefecture-level ...

in China, indicating it had habitat preferences similar to modern lions in many respects. Specimens recovered from

Turolian The Turolian age is a period of geologic time (9.0–5.3 Ma) within the Miocene used more specifically with European Land Mammal Ages. It precedes the Ruscinian age and follows the Vallesian age. The Turolian overlaps the Tortonian The Tort ...

deposits indicate that the fauna living there was much the same, differing only by species in many cases. Among the creatures it shared its environment with were bovids such as '' Parabos'',

Lutung The lutungs, langurs, or leaf monkeys are a group of Old World monkeys in the genus ''Trachypithecus'' (derived from Greek , meaning "rough" and , meaning "monkey"). Their range is much of Southeast Asia (northeast India, Vietnam, southern Chin ...

monkeys, the mastodon ''

Anancus ''Anancus'' is an extinct genus of elephantoid proboscideans ("gomphothere" ''sensu lato'') native to Afro-Eurasia, that lived from the Tortonian stage of the late Miocene until the genus' extinction during the early Pleistocene, roughly from 8.5 ...

'', the rhino ''

Aceratherium ''Aceratherium'' (Greek: "without (a) horn" (keratos), "beast" (therion)) was a genus of rhinoceros of the subfamily Aceratheriinae that lived in Eurasia during the Miocene. Taxonomy ''Aceratherium'' was coined by Kaup (1832) for ''"Rhinocer ...

'', antelopes such as ''

Tragoportax ''Tragoportax'' is an extinct mammal genus belonging to the Bovidae.Miocene

(

'' and ''Miotragocerus'' as well as gazelles and deer, a very large species of hyrax, early goats, various giraffes, camels such as ''

Paracamelus ''Paracamelus'' is an extinct genus of camel in the family Camelidae. It originated in North America during the Middle Miocene but crossed the Beringian land bridge into Eurasia during the Late Miocene, approximately 7.5–6.5 million years ...

'', the horse ''

Hipparion ''Hipparion'' (Greek, "pony") is an extinct genus of horse that lived in North America, Asia, Europe, and Africa during the Miocene through Pleistocene ~23 Mya—781,000 years ago. It lived in non-forested, grassy plains, shortgrass prairie or ...

'', a species of

aardvark The aardvark ( ; ''Orycteropus afer'') is a medium-sized, burrowing, nocturnal mammal native to Africa. It is the only living species of the order Tubulidentata, although other prehistoric species and genera of Tubulidentata are known. Unlik ...

, the chalicothere ''

Ancylotherium ''Ancylotherium'' (from Greek, meaning "hooked beast") is an extinct genus of the family Chalicotheriidae, subfamily Schizotheriinae, endemic to Europe, Asia, and Africa during the Late Miocene-Early Pleistocene (9.0—1.8 mya), existing for app ...

'' and the beaver-like '' Dipoides''. Other carnivores it shared its territory with include the percrocutid '' Dinocrocuta'', the bear '' Agriotherium'', fellow machairodonts ''

Metailurus ''Metailurus'' is a genus of saber-toothed cat in the family Felidae, and belonging to the tribe Metailurini, which occurred in North America, Eurasia and Africa from the Miocene to the Middle Pleistocene. This genus was formally described by O. ...

'' and ''

Paramachairodus ''Paramachaerodus'' is an extinct genus of saber-tooth cat of the subfamily Machairodontinae, which was endemic to Europe and Asia during the late Miocene from 15 to 9 Ma. ''Paramacheirodus'' is one of the oldest known true saber-toothed cat ...

'' and hyenas like ''

Thalassictis ''Thalassictis'' is an extinct genus of terrestrial carnivore in the family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose ...

''. The larger herbivores were likely common prey for ''Amphimachairodus'', and it likely would have competed with ''Agriotherium'' for food, possibly yielding kills to the bear and possibly also stealing kills from hyenas such as ''Thalassictis'' and from ''Metailurus'' when the opportunity arose. In North America, in places such as

Coffee Ranch Coffee is a drink prepared from roasted coffee beans. Darkly colored, bitter, and slightly acidic, coffee has a stimulating effect on humans, primarily due to its caffeine content. It is the most popular hot drink in the world. Seeds of th ...

in Texas, ''Amphimachairodus coloradensis'' shared territory with ''Agriotherium'' as it had in Africa and Eurasia, but also shared territory with the feliform ''

Barbourofelis ''Barbourofelis'' is an extinct genus of large, predatory, feliform carnivoran mammals of the family Barbourofelidae (false saber-tooth cats). The genus was endemic to North America and Eurasia during the Miocene until its extinction during t ...

'' and the canids ''

Epicyon ''Epicyon'' ("more than a dog") is a large, extinct, canid genus of the subfamily Borophaginae ("bone-crushing dogs"), native to North America. ''Epicyon'' existed for about from the Hemingfordian age of the Early Miocene, to the Hemphillian o ...

'' and ''

Borophagus ''Borophagus'' ("gluttonous eater") is an extinct genus of the subfamily Borophaginae, a group of canids endemic to North America from the Middle Miocene epoch through the Early Pleistocene epoch 12—1.8 Mya. Evolution ''Borophagus'', like o ...

'', and herbivores like the camel ''

Aepycamelus ''Aepycamelus'' is an extinct genus of camelids that lived during the Miocene 20.6–4.9 million years ago, existing for about . Its name is derived from the Homeric Greek , "high and steep" and κάμηλος – "camel"; thus, "high camel"; ''a ...

'', the pronghorn antelope '' Cosoryx'', horses like ''

Neohipparion ''Neohipparion'' (Greek: "new" (neos), "pony" (hipparion)) is an extinct genus of equid, from the Neogene (Miocene to Pliocene) of North America and Central America Central America ( es, América Central or ) is a subregion of the Ameri ...

'' and ''

Nannippus ''Nannippus'' is an extinct genus of three-toed horse endemic to North America during the Miocene through Pleistoceneabout 13.3—1.8 million years ago (Mya), living around 11.5 million years. This ancient species of three-toed horse grew up to 3 ...

'', the peccary '' Prosthennops'' and rhinoceroses like ''

Teleoceras ''Teleoceras'' (Greek: "perfect" (teleos), "horn" (keratos)) is an extinct genus of grazing rhinoceros. It lived in North America during the Miocene and Pliocene epochs during the Hemingfordian to the end of Hemphillian from around 17.5 to 4. ...

''. In the Djurab desert in northern Chad, ''Amphimachairodus kabir'' co-existed with fellow machairodonts '' Lokotunjailurus'', ''

Tchadailurus ''Tchadailurus'' is a genus of machairodontine felid from the late Miocene of Chad, Africa. Etymology The genus name ''Tchadailurus'' comes from Chad, the country where the original fossils were found, and the Greek ''-ailurus'', which means c ...

'' and early representatives of the genus ''

''. In addition, animals such as crocodiles, three-toed horses, fish, monkeys, hippos, aardvarks, turtles, rodents, giraffes, snakes, antelopes, pigs, mongooses, foxes, hyenas, otters, honey badgers and the hominid ''

Sahelanthropus ''Sahelanthropus tchadensis'' is an extinct species of the Homininae (African apes) dated to about , during the Miocene epoch. The species, and its genus ''Sahelanthropus'', was announced in 2002, based mainly on a partial cranium, nicknamed '' ...

'' dwelled here, providing ample food. Based on these and other fossils, it is theorized that the Djurab was once the shore of a lake, generally forested close to the shore with savannah-like areas some distance away. The great number of cat species in the environment indicates that there was significant prey and available niches for multiple species of large felids to coexist.Scientific American
/ref>

References

{{Taxonbar, from=Q16974134 Homotherini Miocene mammals of Europe Miocene mammals of Africa Miocene mammals of Asia Miocene mammals of North America Fossil taxa described in 1929 Prehistoric carnivoran genera

Description

Skull

Paleoecology

See also

References