Geologic Time Scale!

So in the geologic time scale there are four main divisions, Eon, Era, Period and Epoch (ranged from longest to shortest in length). The two major eons in world's history so far are the precambrian and phanerozoic. The Precambrian makes up 7/8 of world's history! Also the precambrian eon is divided into two eras, the archean (4.6-2.5 billion years ago) and the proterozoic (2.5 billion years-544 million years ago). The phanerozoic eon is divided into three major eras; the paleozoic, mesozoic and cenozoic. Within the paleozoic era there are 6 different periods beginning with the cambrian (544-490 million years ago), the ordovician (490-433 mya), the silurian (443-418 mya), and the devonian (418-362 mya). The fifth period the carboniferous is actually split into two parts: the mississippian (362-323 mya) and the Pennsylvanian (323-290 mya). The final period in the paleozoic era is the permian (290-251 mya). The second era in the phanerozoic eon is the mesozoic which had three periods in it, the triassic (251-206 mya), the jurassic (206-142 mya) and the cretaceous (142-65 mya). The final era in the phanerozoic eon is the cenozoic, which is actually the era we are in right now! The cenozoic had two periods in it, the tertiary and quaternary. The tertiary period actually had two different parts in it, the paleogene (65-24 mya) and the neogene (24-1.6 mya). The period we are in right now is called the quaternary, which has lasted from 1.6 mya to the present!