Walking with Dinosaurs (1999)

Season 1: Episode 6

The year is 65.5 million BC, and the time is 11:59pm for the dinosaurs. Volcanic activity has begun to choke the land, and dinosaurs are suffering. Few eggs are hatching, poisoned by the toxins in the air. Dinosaurs are on the decline, while mammals are thriving. The pterosaurs are all but gone, replaced by birds, and a massive asteroid is on its final journey to Earth. In this world, the most infamous carnivore stalks the land, the mighty Tyrannosaurus.