AP BIOLOGY

Detailed explanation-1: -The Phanerozoic is divided into three eras: Paleozoic, Mesozoic, and Cenozoic, each of which is further broken into 12 periods.

Detailed explanation-2: -The Phanerozoic Eon is divided into three eras, the Paleozoic, Mesozoic and Cenozoic eras. These were named for the kinds of fossils that were present. The Cenozoic is the youngest era and the name means “new life”. This is because the fossils are similar to animals and plants that are common today.

Detailed explanation-3: -Periods. Just as eons are subdivided into eras, eras are subdivided into units of time called periods. The most well known of all geological periods is the Jurassic period of the Mesozoic era (the movie Jurassic Park, of course, has something to do with that).

Detailed explanation-4: -Two or more periods compose on Era. One Era is hundreds of millions of years in duration.

Detailed explanation-5: -Nowadays, and speaking very generally, geological time is divided first into four great chunks known as eras: Precambrian, Paleozoic (from the Greek meaning old life), Mesozoic (middle life), and Cenozoic (recent life).