Diapaus evolution is truly amazing

This is a condition or mutation which allows mother to hold in suspended animation multiple siblings, having one child at a time, thus she can focus her attention on raising that one child until it is no longer suckling which will allow the twin/sibling to start developing and growing.
I'm not sure how many species are capable of this, or if it's a feature only marsupials possess, I'm just beginning to study this now, so I expect I will be doing an update on this. It just seemed so amazing I wanted to share it. What an amazing survival trait.