10 Questions
Which group of organisms was the main life-form during most of Earth's early history?
Algae and bacteria
When did humans first appear on Earth based on the information provided?
200,000 years ago
What is a mass extinction?
The permanent dying out of a species or a larger group of organisms
Which geologic time unit is the longest?
Eon
What marks the beginning of the Phanerozoic eon?
Variety of life-forms suddenly increased
What event could potentially cause a mass extinction, such as the one that led to the extinction of dinosaurs?
Asteroid or comet impact
What division of geologic time comes after the Proterozoic Eon?
Phanerozoic Eon
Which era is considered the oldest in the Phanerozoic Eon?
Paleozoic era
What major event marks the beginning of the Cambrian period within the Paleozoic era?
Cambrian explosion
Why do scientists have more knowledge about the Cenozoic era compared to earlier periods?
More fossils discovered
Learn about the geologic time scale which organizes major events in Earth's history from its formation to the present day. Discover how life evolved on our planet over billions of years through simple organisms such as algae and bacteria.
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