Kenneth Branagh: Smilodon were very successful predators, and survived up until as recently as ten thousand ago. But eventually, the world around them changed too much. The climate became cooler and drier. The larger prey they specialized in killing disappeared. The saber tooth world came to an end.
Kenneth Branagh: For forty million years, the plains of South America have been ruled by an awesome group of predators. The aptly named 'Terror Birds'.
[after a long pause]
Kenneth Branagh: But recently all this has changed. A new breed of killer has arrived, one fierce enough to terrorize the Terror Birds. Smilodon, the famous saber tooth. The most powerful big cat of all time!
Kenneth Branagh: [about Smilodon] Originally from North America, they came to South America two million years ago. The balance of life here changed as they took over the role of top predators.
Kenneth Branagh: Since splitting from Antarctica thirty million years ago, South America has been isolated from the rest of the world, and as a result, its animals are unique.
Kenneth Branagh: Across a land bridge, came new groups of mammals to colonize this exotic world. Life here would never be the same again.
Kenneth Branagh: Life for a lone male is a grim battle for survival.
Kenneth Branagh: [as the cats creep up on their prey] One false move, and they will have to start all over again.
Kenneth Branagh: [about the Terror Birds] South America is not the only place Terror Birds are doing well. Once the land bridge opened up to North America, they were one of the few creatures to spread north successfully. While these Terror Birds pick over Smilodon's leftovers, their cousins are running riot in Texas and Florida. They only died out just before modern humans appeared.
Kenneth Branagh: [about the Giant Ground Sloth] They might be herbivores, but they will eventually go for carrion to supplement their diet, and when they do, nothing gets in their way.