''Eusmilus'' ('true sabre') is a prehistoric

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

nimravid Nimravidae is an extinct family of carnivorans, sometimes known as false saber-toothed cats, whose fossils are found in North America and Eurasia. Not considered to belong to the true cats (family Felidae), the nimravids are generally considered ...

that lived 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 Continent#Subcontinents, subcontinent of Eurasia ...

during the

Late 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'', "daw ...

Early Oligocene The Rupelian is, in the geologic timescale, the older of two ages or the lower of two stages of the Oligocene Epoch/Series. It spans the time between . It is preceded by the Priabonian Stage (part of the Eocene) and is followed by the Chatti ...

epochs (37.2–28.4 mya).

Taxonomy

There are three valid species of ''Eusmilus'', ''E. bidentatus'' and ''E. villebramarensis''. ''Ekgmoiteptecela'' MacDonald, 1963 was synonymized with ''Eusmilus'' by some authors, but is actually synonymous with ''

Hoplophoneus ''Hoplophoneus'' (Greek: "murder" (phonos), "weapon" (hoplo)) is an extinct genus of the family Nimravidae, endemic to North America during the Late Eocene to Early Oligocene epochs (35–29 mya), existing for approximately . Taxonomy In 20 ...

''. The third species, ''E. adelos'', was described in 2021, and stands as the largest species in the genus. One study performed in 2016 suggests that ''Eusmilus'' is a non-valid genus, and moved all North American species to ''

''. The discovery of ''E. adelos'' meanwhile, suggests that nimravids went along derived evolutionary pathways; conical-toothed, dirk-toothed, and scimitar-toothed, with and that their evolutionary paths split in two, leading to saber-toothed and conical-tooth forms that convergently evolved with those of true felids tens of millions of years later.

Morphology

Most ''Eusmilus'' species had a long body and were about as tall as a

leopard The leopard (''Panthera pardus'') is one of the five extant species in the genus '' Panthera'', a member of the cat family, Felidae. It occurs in a wide range in sub-Saharan Africa, in some parts of Western and Central Asia, Southern Russia, a ...

, though the species ''E. adelos'' was similar in size to a small lion, and thus was the largest of the holplophonine nimravids, reaching the weight of nearly 111 kg ''Eusmilus'' had developed long saber

teeth A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, tear ...

and looked like a

saber-toothed cat 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 ...

, but was actually a so-called ' false saber-tooth'. Most were leopard-sized and rather long-bodied and short-legged compared to modern leopards. Some reached 2.5 metres (8 ft) long. ''Eusmilus'' had lost many other teeth, possessing only 26 instead of the 44 usually seen in carnivore mammals. Its mouth could open to an angle of 90 degrees, allowing the creature to properly use its saber teeth. Bony flanges projected from ''Eusmilus'' ' lower jaw to protect the sabers (this is also seen in the unrelated

marsupial Marsupials are any members of the mammalian infraclass Marsupialia. All extant marsupials are endemic to Australasia, Wallacea and the Americas. A distinctive characteristic common to most of these species is that the young are carried in a po ...

Thylacosmilus ''Thylacosmilus'' is an extinct genus of Saber-toothed predator, saber-toothed metatherian mammals that inhabited South America from the Miocene, Late Miocene to Pliocene Epoch (geology), epochs. Though ''Thylacosmilus'' looks similar to the "Mac ...

'' and

felid Felidae () is the family of mammals in the order Carnivora colloquially referred to as cats, and constitutes a clade. A member of this family is also called a felid (). The term "cat" refers both to felids in general and specifically to the dom ...

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 ...

''). There is fossil evidence of conflict between ''Eusmilus'' and ''

Nimravus ''Nimravus'' is an extinct genus of "false" saber-toothed cat in the family Nimravidae, that was endemic to North America during the Oligocene epoch 33.3—26.3 Annum, mya, existing for approximately . Not closely related to true saber-toothed ca ...

'', another genus of nimravid.

Growth and Development

''Eusmilus'' cubs and adolescents have been discovered, and examinations of their skeletons indicates that their saber-teeth emerged late in life, indicating the animals were dependent on their mothers for a relatively long period. The milk teeth of ''Eusmilus'', upon their eruption, were large enough to allow it to hunt effectively. The added advantage of these milk sabers was that because of the late growth of the permanent sabers, if the milk saber-teeth were damaged, the nimravid had a chance to grow a new set of saber-teeth, allowing it to continue hunting.

References

External links

Nimravidae Oligocene carnivorans Eocene carnivorans Chattian genus extinctions Oligocene mammals of Europe Paleogene France Fossils of France Quercy Phosphorites Formation Fossil taxa described in 1873 Prehistoric carnivoran genera {{paleo-carnivora-stub