7.9.1 Species are lost by the process of extinction

Extinction: loss of a group of organisms

On the phylogenetic tree, an extinction of a specie is noted by a cross → †

7.9.2 Mass extinctions - 5 times

The most famous: The fifth, caused by a massive meteorite; the evidence is a huge crater

7.9.3 Extinction opens up habitats that can be filled by other species

Adaptive radiation is the massive speciation after a mass extinction

7.9.4Humans change environment, leading loss of many species

名言：

灭绝虽易，进化不易，且行且珍惜