Any illustration going beyond the hard parts evidence is (probably) going to be speculative. There is no way of knowing either way. Had the illustration been done without webbed feet, it also might be wrong. Had it been done such, should there be someone complaining that there is no evidence to support the depiction of non-webbed feet?
The more solid evidence to compare are the respective skeletons.
Almost, but not posted in the admin-mode,
Moose