This whole cat family tree thing

is very cool; it's Nicholas Wade's story DNA Offers New Insight Concerning Cat Evolution in the New York Times:

Knowing when each species came into existence, the Johnson-O'Brien team has been able to reconstruct a series of at least 10 intercontinental migrations by which cats colonized the world. The cheetah, for instance, now found in Africa, belongs to a lineage that originated in North America and some three million years ago migrated back across the Bering land bridge to Asia and then Africa.