Geologic Time Scale

Front

What is the Geologic Time Scale?

Back

A system of chronological dating that relates geological strata to time, used by geologists and other Earth scientists to describe the timing and relationships of events in Earth's history.

Front

During which era did fish first appear?

Back

Paleozoic Era.

Front

Which group of organisms evolved first according to the fossil record?

Back

Invertebrates.

Front

What is the oldest time segment in the Geologic Time Scale?

Back

Precambrian Time.

Front

What significant events occurred at the end of the Paleozoic and Mesozoic Eras?

Back

Mass extinctions.

Front

How long ago did the Earth form?

Back

4.6 billion years ago.

Front

What are the three main eras of the Phanerozoic Eon?

Back

Paleozoic, Mesozoic, and Cenozoic.

Front

What is the significance of the Cambrian Explosion?

Back

A rapid diversification of life forms that occurred approximately 541 million years ago, marking the beginning of the Paleozoic Era.

Front

What major event marks the end of the Mesozoic Era?

Back

The mass extinction event that led to the demise of the dinosaurs.

Front

What is the difference between invertebrates and vertebrates?

Back

Invertebrates lack a backbone, while vertebrates have a backbone.