Extinction
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. The species living today probably were not living in the Cambrian period, but their ancestors were.