And they do that despite all the modern non-mammalian species running and flying around that gore3000 can name with hammer-anvil-stirrup earbones. Let me show you the following description of mammals:
Mammals are a group of vertebrates (animals that have a backbone). Certain characteristics separate them from all other animals: mammals breathe air through lungs, give birth to live young, produce milk for their young, are warm-blooded, and have hair or fur. They also have relatively large brains and a variety of tooth sizes and shapes. From: Mammals- Characteristics
As you are no doubt aware, that description is wrong. We both know one mammal that does not fit it - the platypus.
Thanks to that species, the part about live young was taken out of the official definitions. The paleontologists were proven wrong - but only because we had found a live species. If all we had had were the bones of the platypus, then we would though it bore live young and we would have been wrong, very wrong. We would have learned nothing and we would have just re-established the self-fullfilling prophecy of phony paleontology. Further, the part about live young is certainly much more related to the mammary glands than the shape of the ear. There is absolutely no necessary connection between the ear and the other features and if you really believe that species did evolve you would have to admit that sometime during the development of mammals not all of these features were present. That is - unless you wish to posit the ridiculous notion that through super-evo selection all the different characteristics of mammals appeared suddenly at once. ( O wait, is not that what creationists say?).
There is absolutely no necessary connection between the ear and the other features and if you really believe that species did evolve you would have to admit that sometime during the development of mammals not all of these features were present. 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?