Scroll Down for the Answer.
You can see that when we look at this picture, we make assumptions about what we expect was the original shape. In fact, there is no right answer to these questions. The correct answer could be any one of those following options in the next picture. This is similar to having evidence (a fossil) which is in the present (currently in your hand) and you have to make assumptions as to how and when it formed. You can do the methods of science (observations and experiments), but then you have to make assumptions based on those pieces of evidence, but you will never know 100% how it formed that way and exactly (100%) when.
See more about what it means to prove something in science, on page 3: http://www.discovercreation.org/wp-content/uploads/2015/05/n2014-3pg4lo-res.pdf