To summarize the evolutionist case, evolutionists have been increasingly claiming that the fossil ancestors of modern whales have been found, and that a transition can be clearly seen between creatures walking on land (with legs) and whales (which have no legs today), and include the following:
Pakicetus-however, it consisted only of jaw and skull fragments yet its been claimed to be a walking whale.
Basilosaurus has also been offered as an ancestor to whales; while it did have hind limbs, they were far too small to have anything to do with walking. Yet evolutionists agreed that they were clearly functional, not useless, and the most common view is that they were probably used for grasping in reproduction.
Ambulocetus had hind limbs, and could walk; it is thus the latest fossil candidate for whale evolution. However, as explained in Refuting Evolution, it is doubtful that this supposed creature (constructed with some imagination) had anything to do with the history of whales.
Once again, evolution has no legs.