During the Cenozoic Era continents drifted into relatively familiar positions, mountain chains began to emerge, and plants and animals became increasingly recognizable - marking the birth of the modern world.
This was the Age of Mammals. And although they appeared at the same time as dinosaurs, mammals were, initially, small and furtive. Then, as the great reptiles began to disappear, the mammal population increased and soon they were poised to take over.
The Age of Mammals was a time of experimentation and diversification that combined the strange and the familiar.