''Homotherium'', also known as the scimitar-toothed cat or scimitar cat, 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 machairodontine saber-toothed predator, often termed

scimitar-toothed cat 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 ...

s, that inhabited North America,

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sout ...

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 ...

, and

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 ...

during the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in ...

epochs (4 mya – 12,000 years ago), existing for approximately . It became extinct in Africa some 1.5 million years ago. The most recent

n remains, recovered from what is now the

North Sea The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea, epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the ...

, have been dated to around 28,000 years BP. In South America it is only known from a few remains in the northern region (

Venezuela Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in th ...

), from the mid-Pleistocene.

Taxonomy and distribution

The name ''Homotherium'' (

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

: (, 'same') and (, 'beast')) was proposed by

Emilio Fabrini Emilio may refer to: * Emilio Navaira, a Mexican-American singer often called "Emilio" * Emilio Piazza Memorial School, in Port Harcourt, Rivers State * Emilio (given name) * ''Emilio'' (film), a 2008 film by Kim Jorgensen See also * Emílio (dis ...

(1890), without further explanation, for a new subgenus of ''Machairodus'', whose main distinguishing feature was the presence of a large diastema between the two inferior premolars. The lineage of ''Homotherium'' is estimated (based on mitochondrial DNA sequences) to have diverged from that of ''

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 ...

'' about 18 million years ago. ''Homotherium'' probably derived from ''

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 ...

'' and appeared for the first time at 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 ...

–

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58 During the

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in ...

it occurred in vast parts of Eurasia, North America and until the middle Pleistocene (about 1.5 million years ago) even in Africa. A fossil of ''H. crenatidens'' was inadvertently dredged from the bed of the

, which was a flat, low-lying extent of marshy tundra laced with rivers during the last glacial period. It was thought that ''H. latidens'' had gone extinct relatively early, nearly 300,000 years ago, but a rogue specimen of ''H. latidens'' was found in the North Sea of Europe, dated to be from 28,000 years ago. There has also been a discovery of 1.8-million-year-old fossils in

, indicating that scimitar-toothed cats were able to invade South America along with ''

'' during the Great American Interchange. These remains form the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of sever ...

of ''Homotherium venezuelensis''. How long they lasted in South America is not yet evident. ''Homotherium'' survived in Eurasia until about 28,000 years ago. Several Eurasian species have been recognized based mainly on differences in the size and shape of the upper canines and body size: ''H. latidens'', ''H. nestianus'', ''H. sainzelli'', ''H. crenatidens'', ''H. nihowanensis'', and ''H. ultimum''. However, given the range of sizes found in extant large cats, it is likely that they represent a single species, ''Homotherium latidens''. Two species described from early Pleistocene Africa, ''H. ethiopicum'' and ''H. hadarensis—''also hardly differ from the Eurasian forms. On the African continent the genus disappeared about 1.5 million years ago. In North America a very similar species, ''H. serum'', occurred from the late Pliocene until the late Pleistocene. However, both morphological and genetic data suggest that all late Pleistocene ''Homotherium'' individuals worldwide should probably be regarded as members of ''H. latidens''. Remains have been found at various sites between Alaska and Texas. In the southern parts of its range the American ''Homotherium'' co-existed with ''Smilodon''; in the northern parts it was the only species of saber-toothed cat. The American ''Homotherium'' was originally described by the name ''Dinobastis''. Despite ''Homotherium''s vast range and the large quantity of fossil remains from Eurasia, Africa and North America, complete skeletons of this cat are relatively rare. One of the most famous sites of ''Homotherium'' remains is Friesenhahn cave in Texas, where 30 ''Homotherium'' skeletons were found, along with hundreds of juvenile

mammoth A mammoth is any species of the extinct elephantid genus ''Mammuthus'', one of the many genera that make up the order of trunked mammals called proboscideans. The various species of mammoth were commonly equipped with long, curved tusks an ...

s and several dire wolves. The genus ''Dinobastis'' was originally named by

Cope The cope (known in Latin as ''pluviale'' 'rain coat' or ''cappa'' 'cape') is a liturgical vestment, more precisely a long mantle or cloak, open in front and fastened at the breast with a band or clasp. It may be of any liturgical colour. A c ...

(1893). Its type is ''Dinobastis serus''. It was synonymized subjectively with ''Smilodon'' by Matthew (1910) and later with ''Homotherium'' by Churcher (1966), Schultz ''et al.'' (1970), Waldrop (1974), Kurtén and

Anderson Anderson or Andersson may refer to: Companies * Anderson (Carriage), a company that manufactured automobiles from 1907 to 1910 * Anderson Electric, an early 20th-century electric car * Anderson Greenwood, an industrial manufacturer * Anderson ...

(1980), Churcher (1984) and and Carpenter (1988).

Description

''Homotherium'' reached at the shoulder and weighed an estimated and was therefore about the size of a male African lion. Compared to more familiar machairodonts, like ''Smilodon'' or ''

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 ...

'', ''Homotherium'' had comparatively shorter upper canines, but these flat, serrated teeth were still longer than those of any living cat. ''Homotheriums

incisor Incisors (from Latin ''incidere'', "to cut") are the front teeth present in most mammals. They are located in the premaxilla above and on the mandible below. Humans have a total of eight (two on each side, top and bottom). Opossums have 18, wher ...

s and lower canines formed a powerful puncturing and gripping device. The skull was longer than in ''Smilodon'', and it possessed a well-developed sagittal crest, where muscles were attached to power the

lower jaw 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 teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...

. The lower jaw had downwards-flared flanges to protect the upper canines. Its large canine teeth were crenulated and designed for slashing rather than purely stabbing. However, a 2018 study by Figueirido and colleagues found that ''Homotherium'' possessed a bite adapted to clamp and hold while inflicting damage with its canines, similar to a lion's, due to the larger amounts of trabecular bone present in the skulls of the genus. This is unlike the canine shear-bite of ''Smilodon'', which it has been compared to, and this difference in killing bites provides evidence for distinct ecological adaptations. The large upper canines of ''Homotherium'' were likely hidden by the upper lips and gum tissues of the lower lips jaw similar to extant cats, unlike the larger upper canines of ''Smilodon''. The unusually large, square nasal opening, similar to that of the

cheetah The cheetah (''Acinonyx jubatus'') is a large cat native to Africa and central Iran. It is the fastest land animal, estimated to be capable of running at with the fastest reliably recorded speeds being , and as such has evolved specialized ...

(''Acinonyx jubatus''), may have allowed faster

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...

intake, which would have facilitated strenuous cursorial activity and cooling of the

brain A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a ve ...

following such behaviour. The

visual cortex The visual cortex of the brain is the area of the cerebral cortex that processes visual information. It is located in the occipital lobe. Sensory input originating from the eyes travels through the lateral geniculate nucleus in the thalamus and ...

in ''Homotheriums brain was large and complex, also alike that of the modern cheetah, implying that it relied heavily on vision during the hunt.

Diet and habitats

The decline of ''Homotherium'' could be a result of the disappearance of large herbivorous mammals like mammoths in America at the end of the Pleistocene. In North America fossil remains of ''Homotherium'' are less abundant than those of its contemporary ''Smilodon''. For the most part it probably inhabited higher latitudes and altitudes and therefore was likely to be well adapted to the colder conditions of the mammoth steppe environment. The reduced claws, relatively slender limbs, and sloping back all appear to be adaptations for endurance running in open habitats. Genomic analysis supports the hypothesis that ''Homotherium'' was social and well-adapted to life as a pursuit predator. Genes revealing high genetic diversity indicate the genus was far more common than previously assumed due to the preservation bias of the fossil record. The study also revealed that this genus of machairodont was most likely diurnal, and would have mainly hunted in daylight. African ''Homotherium'' species seem to have hunted early Pleistocene species of '' Deinotherium'', likely preferring to target the more vulnerable adolescents or calves in a herd. Due to their saber-teeth, an attack on such thick-skinned prey would have likely been significantly easier and less time-consuming compared to a similar hunt on modern elephants by lions. At the well known Friesenhahn Cave site in Texas, the remains of almost 400 juvenile mammoths were discovered along with numerous ''Homotherium'' skeletons of all ages, from elderly specimens to cubs. Based on this fossil site, ''Homotherium'' was likely a social predator that would have been specialized in hunting young mammoths and that subsequently dragged the kills into secluded caves to eat in relative peace. ''Homotherium'' also seemed to have retained the excellent nocturnal vision typical of most cats, and hunting at night in the arctic regions where many ''Homotherium'' have been found would have been a prime hunting method. The sloped back and powerful lumbar section of ''Homotherium''s vertebrae suggest a bear-like build, and thus that these animals could have been capable of pulling formidable loads; further, broken upper canines - a common injury in fossils of other machairodonts such as ''Machairodus'' and ''Smilodon'' that would have resulted from struggling with their prey - is not seen in ''Homotherium'', perhaps because their social groups would completely restrain prey items before any of the cats attempted to kill the target with their saber teeth. Moreover, the bones of the young mammoths found in Friesenhahn Cave show distinctive marks matching the incisors of ''Homotherium'', indicating that they could efficiently process most of the meat on a carcass and that the mammoths had been deposited in the caves by the cats themselves and not by scavengers. Examination of the bones also indicates that the carcasses of these juvenile mammoths were dismembered after being killed by the cats before being dragged away, suggesting that ''Homotherium'' would disarticulate their kill to transport it to a safe area such as a hidden lair or den and prevent competitors such as dire wolves and American lions from usurping the carcass.

References

External links

The saber-toothed cat of the North Sea
2008, accessed 10/28/2019

Saber-toothed cat jaw

South America gets two more sabercats
{{Taxonbar, from=Q132606 Homotherini Pliocene carnivorans Pleistocene carnivorans Pleistocene extinctions Cenozoic mammals of Africa Cenozoic mammals of Asia Cenozoic mammals of Europe Cenozoic mammals of North America Holarctic fauna Prehistoric carnivoran genera Zanclean first appearances Fossil taxa described in 1890 Pleistocene mammals of North America Pleistocene mammals of Africa Saber-toothed cats