In a May 20, 2008 post entitled Billions of Missing Links: Wombat Pouches, Geoffrey Simmons writes:
A design must be considered improbable if it is highly functional and durable yet too complex to have come about spontaneously or by intermediate steps.
This is a simple rewording of irreducible complexity, an idea that is being destroyed with increasing frequency in the fields of paleontology and in molecular biology. IDers proclaim that the species we have today are too complex to have come about by intermediate steps. Who are they to decide what is too complex? It seems like an arbitrary call to me and set up for future arguments using the moving goalposts fallacy. Besides, systems that once appeared too complex to work without individual parts are now able to be simplified. For example, blood clotting, functional eyes, and the complement system.
The “missing link” brought up in this post is the one of the upside down pouch in wombats:
The wombat has an upside-down pouch. Scientists presume, and it makes sense, that position prevents dirt from entering the pouch when the wombat is digging in the ground. Could there have been transitional species with pouches situated sideways, or did the first wombats have to scoop dirt out of their pouches every day?
The author is using a technique to make evolution sound stupid by bringing up a wombat that would have a sideways pouch or that wombats would have to scoop dirt. Of course the change from right-side-up to upside-down could have simply been in one step. When a wombat came along with a mutation that led to an upside-down patch, it would have a strong advantage in being able to raise healthy young.
This characterization of the wombat is laughable, yet convenient for IDers. I suspect the example was brought up because it is going to be hard to find intermediate fossils of wombat pouch evolution due to the pouch being made of soft tissue. Since soft tissues don’t fossilize, it will be hard to trace its evolution. Unfortunately, there have not been any useful fossils found of wombat ancestors. But then again, present day-like wombats have not been found either, as would have been predicted by ID.