One of the most distinctive features of the fossil record is how species remain unchanged during the geological periods in which they appear. A species preserves the structure it has when it first appears as a fossil until it either becomes extinct or else comes down unchanged to the present, over the course of tens or even hundreds of millions of years. This is clear evidence that living things never evolved. There is no difference between this 50-million-year-old fly fossilized in amber shown here and flies living today.