The concept is clear. I haven't studied the evidence, which is all-important in supporting such a concept. I understand there is some controversy, but I'm really not qualified to leap into that one. The end result is consistent with declaring that mammals and birds are both creations of God, each different in their own way from the reptiles, and all partaking in the glory of creation. See, Vade, this evolution stuff isn't stressing me anywhere near as much as you thought it would.
I'm glad you're not stressed.
In light of the tree thing, what would you say about the line of reptiles from which mammals emerged, versus the one from which birds emerged?