"The start of Cenozoic era marked the dawn of the age of mammals" what do you understand this statement to mean?

This statement means that the beginning of the Cenozoic era, which started around 66 million years ago, was a time when mammals began to dominate the Earth. This era saw the rise of various mammal species, including early primates, rodents, and large mammals such as mammoths and saber-toothed cats. The extinction of the dinosaurs at the end of the Mesozoic era allowed mammals to diversify and thrive, leading to the development of the diverse mammalian fauna we see today.