I was reading the article +29 evidence for macroevolution on talkorigins.org and I've found that a potential falsification of the theory of common ancestor is to find an organism that have some common trait that evolved independently on two different clades.... Some examples would be : a mammal with wings, a bird with mammal glands etc....
Some creationists claim that this is already the case.... And scientists calls it 'convergent evolution'...they give many examples for some placental mammals and marsupial mammals taht they look so much alike more than the other species of the clade where they belong to.
A thylacine, for instance its skull looks exactly like a dog's skull.. And yet, scientists consider thylacine to be more related to a kangaroo than to a dog.
Is that really a falsification of the nested hierarchies that are predicted by evolution from common ancestors?