nested heirarchies as evidence against darwinian evolution

I've read through this thread in it's entirety and have a couple of questions.We have situations currently where an ancestor group splits into very distinct descendant groups - fish vs. mammals for example. Some of the mammals have since evolved features that are typically found only in the fish population (killer whales for example).If science had decided to separate two phylum based on these features, then we would have exactly what rand is looking for, would we not?Is the reason why we don't see what rand is asking for that science, when defining the different high level classification groups specifically chose traits that have not re-evolved due to convergent evolution in order to simplify the classification scheme?