What is an "in the process of evolution" species? What are you looking for, and how would we know it when we found it?
Where are all the freaky evoluting species? Where the heck are all the inbetweens???
The questions you're asking are the equivalent of asking why the offspring of a black parent and a white parent doesn't come out striped or checkerboard. I know I talked to someone else here once who really expected to find animals with four legs plus small, unformed wings, like Spyro, as the transitional between land animals and flying animals:
Is that the kind of thing you think evolution calls for? Because if so, you're mistaken.