# Megantereon

Megantereon is an extinct genus of prehistoric machairodontine saber-toothed cat that lived in Eurasia, Africa and possibly North America from the late Pliocene to the Middle Pleistocene. It is a member of the tribe Smilodontini, and closely related to and possibly the ancestor of the famous American sabertooth Smilodon. In comparison to Smilodon it was somewhat smaller, around the size of a jaguar, though it is thought to have had a similar hunting strategy as an ambush predator.

## Taxonomy and evolution

The type species of Meganteron, M. cultridens was described by Georges Cuvier in 1824, as Ursus cultridens, based on two teeth collected from Pliocene sediments in the Valdarno region of Tuscany, Italy, erroneously considering them to belong to a bear. In addition to the two teeth of Megantereon, Cuvier included another, much older tooth from the late Miocene of Eppelsheim in Germany in the species, which is now known to belong to the unrelated sabertooth cat Machairodus aphanistus. This decision would result in much later taxonomic confusion. In 1824, a fossil mandible of Megantereon from the Les Etouaires site in France was described by Croizet and Jobert as the new felid species Felis megantereon. As scientists were unfamiliar with the concept of sabertooths at the time, they did not realise that a large upper canine from the site belonged to the same species, instead attributing it to Cuvier's Ursus cultridens. In 1828, French paleontologist M. Bravard described a skull with preserved sabers from the Mont Perrier site in France as the species Megantereon megantereon. He suggested that Ursus cultridens should be renamed Machairodus cultridens and should be restricted to cats with serrated saberteeth (which true Megantereon lacked). However, in an 1890 review of sabertooth cat remains from Tuscany, Fabrini used the species name Machairodus (Meganthereon) cultridens to refer to cats which had unserrated canine saber teeth like true Megantereon. There was much taxonomic confusion regarding the issue until 1979 when another review of sabertooth cats from Tuscany was carried out by G. Ficcarelli, who found that Megantereon crenatidens was the valid species according to nomenclatural rules for those sabertooths with unserrated sabers.
The true number of species of Megantereon is controversial, with the number of valid species differing between authors. Historically some authors argued that there was just one species. M. cultridens, but all recent authors agree that there were at least two species, also including the African M. whitei, with some authors arguing for 6 or 7 valid species.
The true number of species may be less than the full list of described species reproduced below:
* Megantereon cultridens (Cuvier, 1824) (type species)
* Megantereon adroveri Pons Moya, 1987
* Megantereon ekidoit Werdelin & Lewis, 2000
* Megantereon falconeri Pomel, 1853
* Megantereon hesperus (Gazin, 1933)
* Megantereon microta Zhu et al., 2015
* Megantereon vakhshensis Sarapov, 1986
* Megantereon whitei Broom, 1937
In 2022, it was proposed, alongside a description of more material, that more Asian species than just M. falconeri: M. nihowanensis, M. inexpectatus (syn. M. lantianensis), and M. megantereon (syn. M. microta) wwre valid. The authors disregarded M. falconeri, however, because of the poor record for that species, and also noted that two specimens – a skull in the Natural History Museum of London and a skull in a museum in Dublin – likely represented a new species (which had been previously noted by other authors).
Remains of Megantereon have been found in eastern and southern Africa, and across Eurasia. The origin of Megantereon is uncertain. Some authors have proposed that the North American M. hesperus is the ancestor of all later Megantereon species, first appearing during the early Pliocene, and dispersing over the Bering Land Bridge around 3.5-3.0 million years ago. Other authors have considered this species, whose holotype specimen is a fragmentary lower jaw, indeterminate remains of Smilodontini, and therefore suggest that Megantereon is only unambiguously known from Afro-Eurasia. Some authors have hypothesised that an early lineage of Megantereon was ancestral to Smilodon, though this has been disputed by others, who considered Smilodon and Megantereon to be sister groups. The oldest confirmed samples of Megantereon are known from Africa from the South Turkwel site in Kenya, dated to about 3–3.5 million years ago, though possible older records are known in Africa dating to 4.4 million years ago. In Europe, the oldest remains are known from Les Etouaries (France), a site which is now dated to 2.78 million years ago, which represent among the oldest records of the genus in Euriasia. Remains from the Siwalik Hills in the northern Indian subcontinent dating to the Early Pleistocene, which are among the largest in the genus, have been attributed to the species M. falconeri.
Megantereon became extinct in East Africa probably no later than around 1.4 million years ago, having become extinct in Africa by 1.3 million years ago. The youngest remains of the genus in Europe date to around 1 million years ago, becoming extinct in the region during the mid-Pleistocene transition possibly to climatic change, which made the region more arid and increased open grassland habitat at the expense of forest. The youngest remains in East Asia (which are the youngest records of the genus globally) date to sometime between 780,000 and 350,000 years ago.

## Description

The skull and jaws are very similar to that of Smilodon, including the presence of very elongate saber canine teeth, with one exception being the lower jaws having flanges projecting downwards near the front of the mandibles. These flanges are somewhat shorter than the length of the canine teeth when the mouth is closed. The saber teeth probably remained exposed when the mouth was closed as is suggested for Smilodon, due to the constraints of its lips and jaw flanges being unable to conceal the sabers without risk of puncture. The study proposed that Megantereon was transitional form between machairodonts that had concealed saber teeth and the exposed sabers of Smilodon. Other differences include the canine saber teeth of Megantereon lacking serrations (present on those of Smilodon) the posterior border of the nasal region being less flat and the zygomatic arch being less upwardly arched and wider than that of Smilodon, and the mastoid process lacking the exaggerated development present in Smilodon.
Species of Megantereon were comparable in size to living leopards or jaguars. Their body proportions were relatively similar to those of jaguars, though their tails were shorter, and their necks more elongate. It had stocky forelimbs, the lower half being lion-sized. It had large neck muscles designed to deliver a powerful shearing bite. Mauricio Anton's reconstruction in The Big Cats and their Fossil Relatives depicts the full specimen found at Seneze in France at 72 centimetres (28 in) at the shoulder. The largest specimens, with an estimated body weight of 150–250 kilograms (330–550 lb) (average 120 kilograms (260 lb)), are known from India. Medium-sized species of Megantereon are known from other parts of Eurasia and the Pliocene of North America. The smallest species from Africa and the lower Pleistocene of Europe have been estimated at only 60–70 kilograms (130–150 lb). However, these estimations were obtained from comparisons of the carnassial teeth. Younger estimations, which are based on the postcranial skeleton, suggest body weights of about 100 kilograms (220 lb) for the smaller specimens.

## Palaeobiology

Megantereon is thought to have been an ambush predator. It is thought to have used its powerful forelimbs to restrain prey, and its long saber teeth to deliver a killing "canine-shear" throat bite, using the muscles of neck to force the saber teeth into the throat while the lower jaw served as an anchor, severing most of the major nerves and blood vessels. While the teeth would still risk damage, the prey animal would be killed quickly enough that any struggling would be feeble at best.
Whether and to what extent Megantereon would have been scansorial and therefore able to climb trees is debated. Arguments in favor rest upon comparisons to modern leopards, and their avoidance of larger predators by the caching of kills in trees. For Megantereon, likely competitors would have included the fellow machairodont Homotherium and the hyena Pachycrocuta. Megantereon also had relatively small carnassial teeth, indicating that once making a kill, it would have eaten its prey at a leisurely pace, either hidden deep in bushes or in a tree away from potential rivals. This indicates a similarity to modern leopards and their lifestyle in that it was probably solitary. Other experts dispute that Megantereon would have been unable to climb proficiently due to its heavy build, and argue that its relatively small claws, stocky limbs and short tail argue against regular climbing. In this case Megantereon would have been unlike the earlier Promegantereon (thought to be its ancestor), but similar to the later Smilodon, which is believed to have spent its time on the ground.
Isotopic analysis of Megantereon whitei from the Venta Micena locality in southeast Spain dating to the Early Pleistocene, around 1.6 million years ago, suggests that at this locality Megantereon hunted large ungulates, including the equine Equus altidens, the muskox-relative Soergelia, and the giant deer Praemegaceros with the prey likely being ambushed from areas on the boundary between forest and savannah.
Although a skull of Homo erectus georgicus (D2280) from Dmanisi in Georgia has been suggested to display bite marks by Megantereon, other authors have suggested that the bite marks cannot be attributed with certainty to Megantereon, and that the giant hyena Pachycrocuta or a member of the big cat genus Panthera are more likely culprits. A 2000 isotope study of remains from the Early Pleistocene Swartkrans cave in South Africa suggests that at this locality Megantereon preyed on hominins, including Paranthropus robustus and early Homo, as well as baboons.
Kills made by Megantereon have been suggested to have left a significant amount of carrion to other predators, with the felid's leftovers probably being frequently being scavenged by both hominins and hyaenids. The abundance of carcasses generated by Megantereon has been proposed as a facilitator of early hominin expansion out of Africa.