"The cheetah is considered one of the earliest divergences in felid evolution, about 8.5 million years ago, compared to the large cats of the ' group, which still shared a common ancestor about 6 million years ago (Adams 1979, Hemmer 1978, Johnson and O'Brien 1997, Neff 1983, Pecon-Slattery and O'Brien 1998, van Valkenburgh et al. 1990). The species known as Acinonyx pardinensis (Adams 1979), which is larger than the modern species, migrated from North America to Asia, India, Europe, and Africa. The modern cheetah evolved into its present form about 200,000 years ago. Genetic research has shown that today’s cheetah populations are descendants of but a few animals that remained after the Pleistocene era about 10,000 years ago, at which point the population experienced a founder event generally referred to as a population bottleneck (Menotti-Raymond and O'Brien 1993, O'Brien et al. 1985, O'Brien et al. 1983). The cheetah somehow survived this time of mass extinction and the population gradually increased."