[PapaBear3625]

The otter spends a lot of time in the water, and has evolved a webbed foot:

which is good for swimming, while still allowing it to walk on land fairly well.

A mammal which spends much more time in the water, like the seal:

has much more prounced webbing on its limbs.

And you finally get to full fins like dolphins have.

[tongass kid]

Having been a student of comparative vertebrate anatomy for many decades I must inform you that your example does in no way support the theory of evolution. The ancient view that ontogeny recapitulates phylogeny is totally out of date. Homologous structures are just that and nothing more and your example in light of gene mapping is without merit. We know that structures may be comparatively homologous but often are not genetically homologous. For evolution to occur the structures must be genetically similar and they are not.