Again, your strawman is that anything transitional is not a fully-formed and functional creature. That's just wrong. For all we know, our own species is in transition to the next thing, if we don't go extinct.
As for the platypus, so many of you picked up the same mantra at once. The platypus is having its 15 minutes of fashion right now.
Anyway, it fits nicely on the tree of life. Its ancestors branched off shortly after the transition from reptiles to mammals. It has a number of expected mammalian features, but it still lays eggs. That's a clue to something the fossil record can't provide, the order in which some of the soft-tissue changes arose.
I've been down this path with gore3000 and Southack and they make a point of seeing nothing. For a description of what the fossil record shows of reptile-mammal transtion, try The Fossil Record by Clifford Cuffey. It's a well-documented transition with a number of clinical features changing visibly in the specimens, notably the jaw and ear bones.
Monotremes have the mammal diagnostics, but their line parted company early with the root stock of later marsupials and placentals. They've been on a separate journey ever since.
The Natural History of the Monotremes.
For a direct rebuttal of creationist arguments, Creationism and the Platypus.
Thus, we might see an amphibian or modern reptile with mammalian three-part ear bones. For some reason, we don't. We might see an insect with feathers, or a bird with fur.
Now serious science knows when and in what lineage of reptiles--the synapsids--those jaw bones moved over into ear bones. If you followed that Cuffey link, you saw the figure and read the text. We shouldn't see the features that evolved there in side branches or in places down the tree of life, only in the things that came up the tree from there, mammals.
Evolution tells a story. It gives us a framework that says certain things should not be found. Piltdown Man was exposed by evolutionists, not creationists, because it had become increasingly clear that it didn't fit the story. It was evidence for the "Out of England" theory, and the only piece of such at that. When better dating techniques became available in the 1950s, what everyone had suspected must be true was proven true.
ID says little except that the supposed "tree" of life is mostly a coincidence. Well, maybe it's like Ford's family of cars. [Problem is, it isn't.] If the designer only designs things that fit the evolutionary tree, well . . . So what?
Not useful. In fact, not scientific.
In 1971, two fossil platypus teeth were discovered in the Tirari Desert in South Australia. They are about 25 million years old, and have been named Obdurodon insignis. The modern platypus has only vestigial teeth which are replaced by horny pads when it is still a juvenile. The fossil teeth are similar enough to these vestigial teeth to allow identification, and they show that ancient platypuses had teeth as adults.
The above is totally laughable - from 2 teeth they determine the characteristics of an animal that does not have any teeth! When I say that paleontology is a fraud, this is what I speak about.