Phanerozoic eon

“Visible Life”Paleozoic Era: old lifeMesozoic Era: middle lifeCenozoic Era: recent life

Geologic Time scale4.6 billion years are divided into

big chunks of time called Eons.Eons are divided into smaller

time periods called Eras. The 3 eras are Paleozoic,

Mesozoic, & Cenozoic.Eras are divided into smaller

time periods called Periods.Periods are further divided into

Epochs.

Precambrian PeriodPrecedes the Cambrian PeriodAccounts for 88% of geologic

timeNot too much known about this

period, and what is, has been discovered within the last 50 years

Not many fossils found in this period due to the changing of rocks (metamorphose)

Paleozoic Era570 million years ago (mya) to

225 myaLongest of the three eras in this

eon

A time of ChangeThis was a time of dramatic

geological, climatic and evolutionary change

Cambrian period: witnessed the most rapid and widespread diversification of life in Earth’s history! (Cambrian explosion)

Life began in the ocean, then transitioned on land

By the end of this era it was dominated by various animals

Paleozoic Era: Common AnimalsTrilobites were common animalsSea scorpions Land plants appeared in middle

Paleozoic.Sharks, rays, and bony fish

existed.Tropical jungle like forest were

prevalent by the end of the era.Insects (some huge) were the

predominant animals.

Permian Period

Devonian Period

Cambrian Period

Mesozoic Era225 mya – 65 mya “Age of the Reptiles”Dinosaurs roamed Earth. (mainly

non-avian)Birds and mammals started

evolving during the last part of the Mesozoic.

This era began and ended with two mass extinctions: Permian-Triassic event, Cretaceous-Paleogene event

Mesozoic Era

Cenozoic EraRecent Life (65 mya to present)

“age of mammals”Ice Age began 3 mya Man evolved during this time

periodPaleogene, Neogene, Quaternary

(periods)