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.14 Phylogeny of cats.
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).