Mesozoic
From Tardis Wiki, the free Doctor Who reference
The Mesozoic was an era of Earth history.
The Cretaceous period was part of the Mesozoic era. The Seventh Doctor left Ace in the upper Cretaceous, around 75,000,000 BC. He returned to find her leading dinosaurs to destroy an alien colony being constructed by slave labour. (PROSE: Living in the Past)
