Wombat Pouch

I think you are making the mistake of assuming that either end opening configuration is the primitive state and that the alternative needs to therefore be superior to it.If you look at the Dasyurids, often considered a more primitive clade of marsupials, many have a very rudimentary pouch which is little more than a circular fold of skin covering the teats (Wooley et al., 2002). What we are seeing in such cases rather than an intermediate step between a backward and forward facing pouch is more likely the ancestral condition from which both of those states are derived. If these were the first forms of pouch to arise then all such rudimentary pouches need to be is better than no pouch at all.TTFN,WK

It would look like the picture I posted above showing exactly that, do you ever read these threads before you post Robert or does seeing anything marsupial related just trigger a natural instinct to post the first thing that comes into your head, which naturally happens to be your usual ide fixe?As for why not a central pouch wouldn't necessarily persist? Because certain configurations favoured increased reproductive success for specific ecological niches. So if a backward facing pouch tends to improve the survival of young in burrowing animals then that would be a factor leading to differential reproductive success of those animals with such a pouch and tending to increase the prevalence of backward facing pouches if the trait was heritable and potentially of favouring over time more backward facing pouches. You haven't really articulated a coherent creationist idea. Saying that a fold of skin 'becomes part of the DNA' is biologically meaningless. Are you thinking of something along the lines of Waddington's 'Genetic Assimilation'?TTFN,WK