Define the term extinct. Also explain the phenomenon of mass extinction.

There have been five main mass extinctions. Match each mass extinction event to its description. 1. Permian extinction 2. Cretaceous-Tertiary extinction 3. Triassic extinction 4. Devonian extinction 5. Ordovician extinction   a. This extinction was most likely due to a change in sea level. During this event, about 60% of all marine species were eliminated. b. This is the best-known mass extinction. It eliminated most large animals, including the dinosaurs. c. This was the most severe extinction event. About 96% of life on Earth died during this event. d. This extinction was most likely caused by climate change. About 80% of land animals died during this event. e. This extinction was most likely due to a change in sea level. It especially affected coral reefs.

What the difference between background extinction and biological extinction?

In biological (paleontological) correlation, the zone created by comparing the start of the age range of one fossil, with the end of the age range of another (as shown below) is called what?  a concurrent age range zone an assemblage zone an index fossil zone a double range zone