Answer:
Paleozoic - When oxygen-breathing organisms first thrived
Mesozoic - Ended with a massive impact
Precambrian - When Earth's atmosphere formed
Cenozoic - Began about 65 million years ago
Explanation:
During the Paleozoic, all of the important things that enable life to prosper were in place in one form or another, leading to an explosion in life, especially among the oxygen-breathing organisms.
The Mesozoic era is an era famous for the dominant animals it had, the dinosaurs, but it is also famous that it ended with a massive impact of an asteroid ], leading to mass extinction.
The Precambrian is the period in which life started, and while the atmosphere was already in existence, it changed significantly and became similar to what we have now, enabling for life to thrive.
The Cenozoic is the last and current era, starting just after the mass extinction that marked the end of the Mesozoic, around 65 million years ago (66 million years ago more specifically).
