I'm looking for scientific evidence......empirical proof that evolution occurred.
So far, I haven't seen any.
Since you seem so certain that you are stating facts, I mistakenly assumed you had proof that what you were saying was accurate, and not just guesswork.
Tribune7's question was why we don't observe something which according to the theory of evolution doesn't happen. Got it so far?
Assuming arguendo that evolution is true, we get a nested hierarchy, i.e. a tree-like structure. Now if you pick one branch from this tree and assign it to a certain category then every branch that sprouts from the original branch is a subset of this category.
So what Tribune7 demands is that such a new branch should be a member of a different superset. But this can only happen if two twigs which originate from branches that diverged a long time ago intersect. An example of this would be a dog giving birth to a cat. This however, contradicts the nested hierarchy predicted by the theory of evolution.
Current canines can change but they will still be classified as canines. It may be necessary to introduce new categories but these categories will remain a subset of the canine category.