Answer:
Mesozoic - the era before the current one
Cenozoic - the current era
Paleozoic - when life first flourished
Precambrian - the first era
Explanation:
The Precambrian is the earliest part of Earth's history, the first era. It's named like this because it preceded the Cambrian - the first period of the Phanerozoic eon, which is the current geologic eon. It lasted from the beginning of Earth (about 4.6 billion years ago) to the beginning of the Cambrian Period (about 541 million years ago).
Paleozoic is an era that lasted from about 541 to about 252 million years ago. During this time, life began to flourish.
Mesozoic is an era that lasted from about 252 to 65 million years ago. It's the era that took place before the current one - the Cenozoic.
