I think you misunderstood parent. There is a natural order on the tree of life starting in the first living organism (the root node) and ending in organisms tha

I think you misunderstood parent. There is a natural order on the tree of life starting in the first living organism (the root node) and ending in organisms that are still around (the leaf nodes). With 'last' parent meant 'last with respect to that order', not necessarily in the sense of 'older' and 'newer' (which correlates with this order, as you pointed out).