Megantereon

Megantereon is an extinct genus of prehistoric machairodontine saber-toothed cat that lived in North America, Eurasia, and Africa. It is closely related to and possibly the ancestor of Smilodon.

Taxonomy
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) existed. 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).

Fossil fragments have been found in Africa, Eurasia and North America. The oldest confirmed samples of Megantereon are known from the Pliocene of North America and are dated to about 4.5 million years. Samples from Africa are dated to about 3–3.5 million years (for example, in Kenya ), s In Europe, the oldest remains are known from Les Etouaries (France), a site which is now dated to 2.78 million years ago. A North American origin of Megantereon has therefore been suggested. However, recent fragmentary fossils found in Kenya and Chad, which date to about 5.7 and 7 million years, are probably from Megantereon. If these identifications are correct, they would represent the oldest Megantereon fossils in the world. The new findings therefore indicate an origin of Megantereon in the Late Miocene of Africa.

The youngest remains of the genus in Europe date to around 1 million years ago, with the youngest remains in East Asia dating to around 400,000 years ago.

Description
Megantereon was built like a large modern jaguar, but somewhat heavier. It had stocky forelimbs, the lower half being lion-sized. It had large neck muscles designed to deliver a powerful shearing bite. The elongated upper canines were protected by flanges at the mandible. Mauricio Anton's reconstruction in The Big Cats and their Fossil Relatives depicts the full specimen found at Seneze in France at 72 cm at the shoulder. The largest specimens, with an estimated body weight of 150 – (average 120 kg), 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 –. 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 kg for the smaller specimens. More recent sources agree with this and estimate Megantereon from the European lower Pleistocene at 200 –.

Palaeobiology


In Europe, Megantereon may have preyed on larger artiodactyls, horses or the young of rhinos and elephants. Despite its size, Megantereon would have also likely been scansorial and therefore able to climb trees, like the earlier Promegantereon (thought to be its ancestor), but unlike the later Smilodon, which is believed to have spent its time on the ground. 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.

It is now generally thought that Megantereon, like other saber-toothed cats, used its long saber teeth to deliver a killing throat bite, 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.

In Dmanisi, Georgia, evidence also exists that Megantereon interacted with hominids from a Homo erectus skull. The skull, designated D2280, indicates wounds to the occipital matching the dimensions of the sabre-teeth of Megantereon. From the position of the bite marks, it can be inferred that the hominid was attacked from the front and top of the skull, and that the bite was likely placed by a cat which saw the hominid as a threat. Other machairodont bites have been found on rival predators, including other machairodonts, in past fossil discoveries, the wounds indicating aggressive behavior towards potential competition. The hominid likely managed to escape the Megantereon, as no evidence points to predation or scavenging, although the resulting wounds were fatal. Further evidence of Megantereon being a hunter of hominids exists as carbon isotope ratios in teeth at Swartkrans. When compared with its fellow machairodont, Dinofelis, which shared the same environment, it was discovered that Megantereon was more likely to prey on hominids than Dinofelis, which preferred to hunt grazing animals, based on carbon isotope ratios of its own teeth.

Kills made by Megantereon were an important source of carrion in its ecosystem, with the felid's leftovers 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.