I have a hard time imagining how mammalogists don't go insane with so many
major groups of mammals that have utterly unknown relationships.
I suppose they got used to it. After all it has been the normal state of
affairs for many clades throughout the 20th century.
That never happens with dinosaurs.
That's because there aren't as many of them (except Neornithes) and because
they haven't undergone such an explosive radiation (again except
Neornithes).
The ornithologists didn't have as many confusing fossils to deal with, but
apart from that, their situation is similar to that of placental
phylogenetics. I just say Metaves-Coronaves.
Then there's the fact that (due to its successes) Mesozoic dinosaur
phylogenetics is an arms race: just about every published matrix is bigger
than all its predecessors. Mesozoic mammal phylogenetics now has its own
arms race (the *Yanoconodon* matrix has 436 characters, the
*Volaticotherium* one has 438). Placental phylogeny never got one started.
Maybe Tabuce et al. will turn out to be the starting point, though 52
characters are not promising...