There is quite a bit of fun in building a little web of questions and answers throughout StackExchange. (Let's call it an exercise in interdisciplinarity.)
"Molecular biologist Robin Holliday has written that the apparent lack of biological wheels argues against creationist or intelligent design accounts of the diversity of life—for, free of the limitations imposed by evolution, an intelligent creator would be expected to deploy wheels wherever they would be of use." (See Wikipedia.)
Now, that (let's call it A) didn't strike me as particularly strong argument, given that there are other (potential) explanations for the apparent lack of wheeled animals. One consists in the developmental and anatomical constraints (B), and another one consists in the disadvantages of wheels (C).
Therefore, I asked for an explanation on Biology SE and stipulated that I would like to see included in the answers what assumptions would be falsified once a wheeled animal would be discovered, hoping that that will produce thoughtful answers. However, perhaps I myself just didn't think about this enough.
In the meantime, however, it struck me that one can get a bit philosophical about this. In particular if one asks: How many correct explanations can there be for something not to exist? Must they be dependent? Must they be independent? Is an explanation the same thing as a reason? Etc. I vaguely recall that some philosophers like to discuss unicorns, and this seems related.
So, I ask you, can you please shed some light on the exact logical structure of this problem, as the use of formal logic seems appropriate?