The evolution of the sabre-toothed cat seems to have begun with the most primitive group of placentals, the Edentates. After the Edentates branched off, the other palcentals broke to form five supraordinal groups. These groups included Insectivora, Carnivora, Glires, Archonta, and the Ungulates.

Figure.15  Skeletal structure of Creodont.

Two groups of carnivorous mammals are recognized: the order Carnivora and the extinct Creodonts. Most Creodonts went extinct near the late Eocene while, the order Carnivora began to radiate into two different branches: the Caniformia and the Feliforma. The Feliforma branch of the order Carnivora is uncertain but is thought to be linked to an early Eocene miacid. The true cats, Noefelids, are not seen until the early Miocene, where Proailurus is found. From Proailurus various cat genera are known, including the sabre-toothed cat. There was also another family of carnivores that were similar in appearance to the cat, called the Nimravids. The Nimravids are called the Paleofelids (false cats). They possess cat-like features, especially in the teeth and jaw, but this is due to evolutionary convergence.

Some researchers believe that the Paleofelids are more closely related to Caniforms, while others believe them to be a distant relative to the Feliforms (Pothero 1998).

---