The plants and animals that live in Illinois have changed over time.

Muskox lived in Illinois 13,000 years ago.

Most of the plants and animals that now live in our state are very different from those that lived here long ago. Over time, living things change. New species evolve. Some disappear. The fossil record tells us that most of the species that once lived on our planet are gone. It seems that extinction is the rule of nature, rather than the exception.