Evolution Of The Big Cats

The term "big cat" is used to refer to any of the five living members of the genus Pantheratigerlionjaguarleopard, and snow leopard.
It is estimated that the ancestors of big cats, split away from the Felinae subfamily about 6.37 million years ago. The Felinae, comprises mostly small and medium-sized cats, that includes domestic cats, cougars, and cheetahs. 
Recent studies show that the snow leopard and the tiger are sister species, while lions, leopards, and jaguars are more closely related to each other.  The tiger and snow leopard split from the ancestral big cats approximately 3.9 million years ago.  The ancestor of lions, leopardw, and jaguars split from other big cats from 4.3–3.8 million years ago.