Period: 541 BCE to 252 BCE
Paleozoic-Guide fossil:Trilobites (arthropods).
-Geological event: Big explosion of life.
-Climate event: Greenhouse effect, great volcanic activity and formation of the super continent Pangeas.
Period: 252 BCE to 66 BCE
Mesozoic-Guide fossil: ammonites (cephalopod mollusk).
-Geological event: The Atlantic Ocean originates and the continents begin to separate.
-Climate event: There are no glaciations due to the warm climate.
Period: 66 to