stevebee92653 wrote:
The single common ancestor to all members of any group, say mammals, had to have all of the organs and bio-systems extant and common to that now modern group. Map it out yourself. Organs and bio-system cannot be "picked up along the tree branch", or those O and BS would miss many of the modern species, and we would see a very strange mix of organs and bio-systems today in that one group.
But that's exactly true. The single common ancestor to all mammals - as you say - had all of the organs and biosystems already. Heart, yep, circulatory system, yep, lungs, yep, liver, yep, stomach and excretory tube to anus, yep, backbone, yep, spinal cord and brain, yep, two eyes, yep, two ears, yep ...
Well, you should be able to get the drift. All of those "complicated" biosystems were already present in the very first mammal; all of its various mammal descendants inherited them and did not have to evolve them separately, no matter where they moved to or when exactly they evolved.
Did you really not know this already ? Did you really think that two different mammal species each separately evolved nipples ?
Please confirm that you understand this now.