Marsupial evolution

It is often said, it support of evolution, that the marsupials are "more similar" to each other then to their similar looking placental counterpart. This was one of the major lines of evidence that convinced me of evolution. But I would like to dig deeper into this. When scientists say they are more similar, to they refer to bone structure or genetic similarities? Indeed, these must both be true if in reality they evolved from a more recent common ancestor then they share with the placentals; but exactly which lines is more obvious to scientists? Is there a site where the specific evidence is drawn out, perhaps with pictures of the bone structures or descriptions of similar mutations in non-coding dna shared by the marsupials but not the placentals?Thank you.

Thread copied to the Marsupial evolution thread in the Biological Evolution forum, this copy of the thread has been closed.