Felidae Oligocene, about 25 million years ago, with the appearance of "Proailurus" and "Pseudaelurus". The latter species complex was ancestral to two main lines of felids, the cats in the extant subfamilies and a third major group of extinct cats, which are assigned to the subfamily Machairodontinae. The machairodonts included the saber-toothed cats such as the "Smilodon". The "false sabre toothed cats", the Barbourofelidae and Nimravidae, are not true cats, but are closely related and together with Felidae and other cat-like carnivores (hyaenas, viverrids and mongooses) make up the feliform carnivores. Results of mitochondrial analysis indicates that all the Felidae descended
Felidae based on phenotypical features: the Felinae, the Pantherinae, the Acinonychinae (cheetahs), the extinct Machairodontinae, and the extinct Proailurinae. Molecular phylogenetic analysis suggests that living (extant) felids fall into eight lineages (clades). The placement of the cheetah within the Puma lineage invalidates the traditional subfamily Acinonychinae, and recent sources use only two subfamilies for extant genera. The eight lineages divide between these as follows: The last four lineages are more related to each other than to any of the first four, so form a clade within the subfamily Felinae of family Felidae. The following is the complete list of genera within