Extinction is one of the major features of evolution. A species is extinct when no members of the species are still alive.
All species become extinct sooner or later. The end of a species may happen for many reasons. It may be caused by habitat loss or by being overhunted, or by a major extinction event. An example of an animal that is now extinct is the Dodo, from over-hunting. Another quite different way for a species to end is by species-splitting, known as cladogenesis. Probably, none of the species living today was living in the Cambrian period, but their ancestors were.
endangered species are those which may become extinct. A report from Kew Gardens suggests that one fifth of plant species may be at risk of extinction. Fossil species sometimes reappear millions of years after they were thought to be extinct. These cases are called Lazarus taxa.

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