The group of "warm-blooded animals" is polyphyletic.
Polyphyly is a term in cladistics. It describes a group of organisms whose last common ancestor is not a member of the group. Another way of expressing this is to say that polyphyly includes groups some members of which are descended from ancestral populations.
The diagrams show that birds and mammals are indeed related, but only at the level of the early amniotes. In terms of evolution, there is a vast gulf between them.