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Dnsr Notes 25

Aliens, Asteroids, and Volcanoes

What percentage of dinosaurs are now extinct? 99.9%
How long did dinosaurs thrive for? 150 my
How many species of dinosaurs exist today? 10,000
How does background extinction compare to mass extinction? Background extinction continually occur and are isolated extinctions. Mass extinctions occur great and small but are still substantial events.
What are the five mass extinctions? End-ordovician, late devonian, end-permian, end-triassic, end-cretaceous
When was the end-Ordovician? (445 Mya)
Late Devonian? (374 mya)
end-permian and what percentage went extinct? (252.5 mya) 80%
end-triassic (201.5 mya)
end-cretaceous (65.5 mya)
What was the K-T extinction? Cretaceous-tertiary
What are the three main hypoth
Created by: Chelseagirl2508