?
How many periods are?
12
What is the key event more recent?
Human evolve
In how many millions years the earliest life starts?
3500
How many eons are?
4
How many eras are?
6
In what period the dinosours extinct?
Cretaceous
What is the period that lastest the longest?
Precambrian
In how many millions years ago the Mesozoic era start?
240
In what period the invertebrates become common?
Cambrian
What period began 410 millions years ago?
Devonian