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

This era is known for the appearance of the first reptiles and abundant marine organisms

What is the Paleozoic Era?

100

The "Age of Reptiles" is used in reference to this era because of the dominance of dinosaurs.

What is the Mesozoic Era?

100

This era which began about 66 million years ago, is often referred to as the "Age of Mammals."

What is the Cenozoic Era?

100

Fossils that are found in many parts of the world but only existed for a short period of time are known as these.

What are index fossils?

200

 This event at the end of the Paleozoic Era led to the extinction of nearly 90% of marine species.

What is the Permian-Triassic extinction?

200

This event marked the end of the Mesozoic Era and the extinction of most dinosaur species.

What is the Cretaceous-Paleogene extinction?

200

This mass extinction at the end of the Cretaceous period allowed mammals to rise at dominance.

What is the Cretaceous-Paleogene extinction?

200

This type of fossil is created when minerals replace the organic material in dead plants or animals, keeping their shape.

What are permineralized fossils?

300

The Paleozoic Era spans from 541 million years ago to this number of millions of years ago.

What is 252 million years ago?

300

This period is known for the rise of dinosaurs, diverse and abundant.

What is the Jurassic period?

300

In addition to the Quaternary period, the Cenozoic Era is divided into two major periods - the Paleogene period and this later period.

What is the Neogene period?

300

This type of fossil is formed when an organism is trapped in tree resin and later fossilizes into amber.

What are amber fossils?

400

This was the dominant group of animals during the Cambrian period of the Paleozoic Era.

What are trilobites?

400

This was the appearance of a non-mammal land bound species in the Cretaceous period.

What are early flowering plants?

400

This ice age event significantly shaped Earth's climate and geography.

What is the Pleistocene Ice Age?

400

This type of fossil is formed by the imprint of an organism and preserves fine details of its surface and texture.

What are molds and casts?

500

The largest mass extinction in Earth's history is associated with a massive warming event caused by these factors.

What is volcanic activity and increased CO2 levels?

500

The Triassic period is known for the appearance of this major reptilian group.

What are dinosaurs?

500

The Paleocene epoch contained the rise of these mammals.

What are early primates?

500

Fossils of these creatures are used to date layers of rock because of their wide geographic distribution and short lifespan.

What are index fossils?

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