EXTINCTION

When North America collided with the South American land mass, the North American populations of Smilodon moved into the south and into the territory of the Terror Bird, which stood ten feet tall (3 m). A fierce competition developed between the top predators of the North and South Americas. The Birds were out-matched by the mammals, and 1 million years ago when the Smilodon populator was at the peak of its existence the Terror Birds soon became extinct. The end of the Ice Age in North America saw the decline of many large animals, both predators and herbivores alike. The loss of large prey and the hunting competition from prehistoric humans may have speeded the demise of Smilodon from North America. It is strongly suspected that Smilodon outcompeted the indigenous saber-toothed marsupial Thylacosmilus, which lived in South America during its period of isolation prior to the faunal exchange with North America that followed formation of the Isthmus of Panama. The competition for prey (such as Toxodon and Macrauchenia) with the invading Smilodon shortly led to the extinction of the marsupial sabre-tooth.