There are several biology themes that conspire against the notion that evolution is a random, undirected process. Convergent evolution, as discussed in this article, is one of them. You'll see that convergent evolution is so common, that is makes parsing family trees difficult.
"It is reasonable to think that two birds with similar characteristics—webbed feet for swimming, for example—are related. Until recently, looking at such characteristics was the best tool scientists had for building the bird family tree.But evolution's great trick is to find the same solution, over and over again, to a common problem. The bat family and the bird family, for example, both evolved wings, but separately. The fact they both have wings does not necessarily mean they inherited them from a common ancestor.
Scientists call it "convergent evolution," two creatures separately "converging" on the same solution to a common need, and for scientists it can be maddeningly confusing."
