Paleozoic Era
Mesozoic Era
Cenozoic Era
Types of Fossils/Index Fossils
100

Fish first began to appear in Earth's fossil record during this period.

What is the Cambrian period?


100

The Mesozoic Era is specifically known for the first appearance of this species. 

What are dinosaurs?

100

The first early primates began to appear during this time, also known as the ancestors of modern mammals. 

What is the Paleogene period?


100

Any evidence of earlier life which is preserved in rock.

What is a fossil?


200

The biggest extinction on Earth occured at the end of this period, where 90% of Earth's species were wiped out. 

What is the Permian period?

200

The first dinosaurs began to appear in this period.

What is the Triassic period?

200

The extinction of many large mammals occured during this event.

What is the Ice Age extinction?

200

This type of fossil is formed when a species shape is left behind in a rock after decaying.

What are molds?


300

The first land plants began to appear in this period.

What is the Silurian period?


300

The first birds began to appear in this period.

What is the Jurassic period?


300

This environment began to spread and become more common around the Earth during this time period.

What are grasslands? 

300

This type of fossil is formed from the feces of animals which provides a good understanding of their diets in the past. 

What are corpolites?

400

This group of marine species began to form during this time period. 

What are corals? 

400

The supercontinent, Pangea, began to break apart in this era which lead to the continents that exist today.

What is the Mesozoic Era?

400

Several active volcanoes that were formed during the Cenozoic Era.

What are the Cascade volcanoes?

400

These fossils are created from soft parts of an organism which are preserved as thin layers of carbon, showing the details of their anatomy.


What are carbonaceous films?

500

During the Paleozoic Era, swamps played a big part in the formation of coal due to dead plant material. 

What are coal swamps? 

500

Throughout this period, the continents continued to move apart which lead to the expansion of the Atlantic Ocean.

What is the the Cretaceous period?

500

This time marks when North and South America connected through the formation of a natural bridge. 

What is the Isthmus of Panama?

500

These fossils originate from species that didn't have a long life span but aided scientists in determining the age of rocks.

What are index fossils?

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