Actually, it relates to the disappearance of the multi-boned lower jaw. Why would I have the slightest reluctance to admit that sometime during the development of mammals, not all features were present? Early in the development of mammals, they weren't really mammals and essentially none of the various diagnostic features were present. Well, maybe that's not quite right.
I know you remember this figure!
Here's an exception to the rule about ear bones. All but the top two are reptiles, but some of them have the ear bones! (But they aren't around anymore. All the synapsids seem to be real mammals now.)
Notice that even the primitive one at the bottom also has slightly differentiated teeth, the start of pair of canines. The point is, only this one lineage of reptiles, none of whom are still around as reptiles, underwent these changes. Evolution says you have to look up the tree of life from there for similar features, not on side branches or below. (OK, there's a complicating factor called convergent evolution which can be hard to sort out in the fossil record sometimes.) Creation/ID shrugs and says "He can do what he wants. Mustn't second-guess."
Never mind for a moment about what's science. What's actually telling you something and what isn't?