_Monotrematum_ has "teeth and femora very similar to those of undoubted fossil and living platypuses" (Phillips et al.)
Femora? When were femora discovered? I thought all that was known was one lower and one upper molar?
Also, I should make explicit that mammalologists have no qualms about referring isolated bones to isolated teeth from the same site if the sizes appear to fit. (There was an interesting case of that at the SVP meeting... more on that later.) There may well be two monotreme taxa represented by that material rather than one.