What is Extinction?Extinction is the end of a

group of organisms (normally a species).

Extinctions are a normal

part of evolution.

Background Extinction Rate• Average Life Span of a species• About 1 extinction/million species/year• Over 98% of all species ever to live on earth

are now extinct.• How do we measure extinction rates using

fossils?Type of Animal Average Species Life Span

All Fossil Groups .5 - 5 million years

Invertebrate 11 million years

Mammal 1 million years

Mass Extinction: 50% or more of the living species die out suddenly

http://dsc.discovery.com/earth/wide-angle/mass-extinctions-timeline.html

With all this extinction, how do we still have so many species on Earth?

Are we currently in a Mass Extinction?

Some scientists say that up to half of all theorganisms on Earth right now will be extinct by 2100