"The start of Cenozoic era marked the dawn of the age of mammals" what does this mean and reasons to explain this statement?

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's ecosystems. Prior to this era, dinosaurs were the dominant land animals, but their extinction at the end of the Mesozoic era paved the way for mammals to rise to prominence.

There are several reasons to explain why the Cenozoic era marked the age of mammals:

1. Adaptive radiation: With the extinction of the dinosaurs, mammals were able to rapidly diversify and fill the ecological niches left vacant by the dinosaurs. This led to the evolution of a wide variety of mammalian species with different adaptations for different environments.

2. Evolution of new mammalian groups: During the Cenozoic era, many new groups of mammals evolved, including primates, rodents, carnivores, and ungulates. These groups diversified and spread to different parts of the world, becoming the dominant land animals in their respective ecosystems.

3. Climate change: The Cenozoic era was a time of significant climate change, with periods of warming and cooling that shaped the evolution and distribution of mammalian species. Mammals were able to adapt to these changing environments, leading to their success in the era.

4. Rise of humans: The Cenozoic era also saw the evolution and rise of humans, who belong to the mammalian order Primates. Humans have had a significant impact on the Earth's ecosystems and have further solidified the dominance of mammals in the modern world.

Overall, the Cenozoic era marked the age of mammals due to the extinction of dinosaurs, the rapid diversification of mammalian species, the evolution of new mammalian groups, climate change, and the rise of humans. These factors combined to make mammals the dominant land animals on Earth during this era.