Phanerozoic eon “Visible Life” Paleozoic Era: old life Mesozoic Era: middle life Cenozoic Era: recent life

Geologic Time scale 4.6 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 Period Precedes the Cambrian Period Accounts for 88% of geologic time Not 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 Era 570 million years ago (mya) to 225 mya Longest of the three eras in this eon

A time of Change This 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 Animals Trilobites were common animals Sea 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 Era 225 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 Era Recent Life (65 mya to present) “age of mammals” Ice Age began 3 mya Man evolved during this time period Paleogene, Neogene, Quaternary (periods)