Megantereon is an extinct genus of prehistoric machairodontine saber-toothed cat that lived in North America, Eurasia, and Africa from the late Pliocene (or possibly the late Miocene) 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 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. The true number of species may be less than the full list of described species reproduced below: 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 ). 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. 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. '' 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 at latest 400,000 years ago.

Description

Species of Megantereon were comparable in size to living jaguars. 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

Megantereon is thought to have been an ambush predator. It is now generally thought that Megantereon, like other dirk-toothed 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. 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. 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.