What geologic era is known as the age of mammals?

Mammals proliferated during the Cenozoic (recent age--since the end of the Cretaceous 65 million years ago). There were mammals before the Cenozoic, but dinosaurs were the most abundant fauna of that era. Reptiles, birds, fish, and turtles continue to exist. There are over 8000 species of birds, but fewer than 6000 species of mammals.