You want to claim that fins are not a fish parts. Fine, but realize that it is arguableNo, it's not. That's the whole point - they perform the same function, and are superficially similar, but are anatomically completely different.A draft version of the platypus genome sequence was published in Nature on 8 May 2008, revealing both reptilian and mammalian elements, as well as two genes found previously only in birds, amphibians, and fish. (wikipedia)Exactly. So they are not bird parts; they are vertebrate parts.