Evolutionary theory does not predict chimeras or half-formed organisms or structures. Were such a thing discovered you could go ahead and call evolutionary theory defeated.
See, the way evolution works is like this. Look at an old picture of your grandparents. They probably look similar, but not identical, to your parents. Now take a look at an old picture of your parents. They probably look similar but not identical to you. Now you, you look similar to your parents, and slightly less similar to your grandparents. Your parents were the transitional form between you and your grandparents. Literally,
that is what transitional form means in evolutionary biology. Extremely slight modifications that add up over many generations.
In addition, there are organisms demonstrate a half-way stage between two major developments. Above was a link to the
tiktaalik. Look at the picture. It's a fish, right? But look at its fore-fins. It walks on them. It is a fish that walks, and a clear example of the transition from aquatic chordates to land chordates.