Marsupial evolution

question from a layman.did modern placental mammals evolve from marsupials?they had a common ancestor that presumably didn't lay eggs. what was this ancestor?i've been searching the web a bit and can't seem to get a straight answer on this. Edited by carl, : No reason given.

thanks for your replies mantis and ned. an interesting topic.was just thinking that when the two lines diverged mammals did not yet appear to have the ability to make a fully-formed placenta. so would that make the common ancestor more like a marsupial than a placental mammal? Edited by carl, : No reason given.

Well an alternative to placentals evolving from marsupials, I guess, is that is that the marsupials split from a monotreme-like ancestor earlier than the placentals.That might account for why both the monotremes and marsupials suckle young that seem almost embryonic. It's interesting that the female echidna (the other monotreme) develops a simple pouch in which to lay her egg. The "puggle" is not much bigger than a jellybean when hatched and is carried around in her pouch for about three months.I do think marsupials are a more ancient lineage than placentals, but, as you say, the fossil record seems to be ambiguous on this.Thanks for your help on this fascinating subject.Edited by carl, : No reason given.Edited by carl, : clarityEdited by carl, : No reason given.Edited by Adminnemooseus, : Put upper-case letters where they belong.