Question

Oxygen was said to first be present during the Paleozoic Era.

True
False

Answer 1

False. Now here is why. There was of CO2 in the air right after the Earth's formation. So when things started to evolve, they evolved to breathe IN CO2 instead of Oxygen. But then one particular type of algae came along and created "The Great Oxygenation Event" which killed off most of those CO2 breathing creatures. I hope this helps!