Smilodon, often called a saber-toothed cat or incorrectly a saber-toothed tiger, is an extinct genus of machairodonts. This saber-toothed cat was endemic to North and South America, living during the Pleistocene epoch (2.5 mya—10,000 years ago).
The genus is currently divided into three species : Smilodon gracilis, Smilodon populator, and Smilodon fatalis.
Large numbers of these animals have been found in the famous tar pits at Rancho La Brea in California, making them among the most well known of the ancient predators. The animals full range actually extended throughout North and South America. The earliest species is Smilodon gracilis, known from about 2.5 MYA . It is also the smallest of the three.
Smilodon populator was the largest. It was about the size of a modern lion, and was found mainly in eastern South America. This species appeared as early as 1 MYA. Smilodon fatalis is slightly smaller than S. populator. It ranged from North to South America.
These cats existed until around 10,000 years ago, when the last became extinct. To compare, all three have coexisted with humans for thousands of years. It is estimated by some anthropologists that humans may have arrived in the Americas as early as 25,000 years ago, although most would estimate closer to 11,000 years.