Answer:
Precambrian - the first era
Paleozoic - when life first flourished on Earth
Mezozoic - the era before the current one
Cenozoic - the current era
Explanation:
The biggest part in Earth's geological history comprises of Precambrian era. It lasted from the formation of earth all the way untill Cambrium, which marked the beginning of Paleozoic. It's main characteristic is the rich sea, plant and insect life. After Paleozoic, Mezozoic ensued and the dinosaurs marked this period. After their extinction, Cenozoic started, era that still lasts.
