Recall that for evolution to be plausible, it must take place slowly. A chicken egg just does not give birth to a snake.
This shows the structurally closest fossilized fish and amphibian. Notice the dramatic jump in the structure. The emergence of a pelvis and jointed back legs. A casual study of these skeletons reveals numerous differences. Consider too that only 10 % of the biology of an organism is found in the skeleton. Even skeletons that look similar may have very different soft tissue anatomy.
Reference: M. Denton, Evolution: A Theory In Crisis, pg.167
10%of biology...estamate: M. Denton, Evolution: A Theory In Crisis, pg.177