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.

Fossil range
Fossil fragments have been found in Africa, Eurasia, and North America. The oldest confirmed records of Megantereon are known from the Pliocene of North America and are dated to about 4.5 Million years. About 3-3.5 Million years ago, it is firmly recorded also from Africa (for example, in Kenya[1]), about 2.5 to 2 Million years ago also from Asia. In Europe the oldest remains are known from Les Etouaries (France), a site which is now dated to less than 2.5 Million years old. Therefore a North American origin of Megantereon has been suggested. However, recent findings of fragmentary fossils from Kenya and Chad, which are dated to about 5.7 and 7 Million years, respectively, are probably from Megantereon. If these identifications are right, 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.[2]

At the end of the Pliocene it evolved into the larger Smilodon in North America, while it survived in the Old World until the middle Pleistocene. The youngest remains of Megantereon from east Africa are about 1.5 million years old. In southern Africa, the genus is recorded from Elandsfontein, a site dated to around 700,000-400,000 years old. Remains from Untermaßfeld show that Megantereon lived until 900,000 years ago in Europe. In Asia, it may have survived until 500,000 years ago, as it is recorded together with Homo erectus at the famous site of Zho-Khou-Dien in China. The only full skeleton was found in Senéze, France.

Description
Megantereon was built like a large modern jaguar, but somewhat heavier. It had stocky forelimbs with the lower half of these forelimbs 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 as 72 centimetres (28 in) at the shoulder. The largest specimens, with an estimated body weight of 90–150 kilograms (200–330 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 to only 60–70 kilograms (130–150 lb).[3] However, these estimations were obtained from comparisons of the carnassial teeth. Younger estimations, which are based on the postcranial skeleton, lead to body weights of about 100 kilograms (220 lb) for the smaller specimens.[4] In agreement with that, more recent sources estimated Megantereon from the European lower Pleistocene at 100–160 kilograms (220–350 lb).