The ostrich v. Darwin.

Ostrich Kneecaps — Another Enduring Mystery for Darwinism
Cornelius Hunter  

Why do ostriches have four, rather than two, kneecaps? new study has found several possible biomechanical advantages. Perhaps they allow the ostrich to straighten its leg more quickly, helping the animal to run quickly. Perhaps the lower kneecap protects the joined tendons crossing the front of the knee.

One reason that does not help to explain the ostriches four kneecaps is evolution. That is because this unique design is not predicted, and makes no sense, on the theory.

As  one article admits: “Bizarrely, many of the ostrich’s closest relatives don’t have kneecaps at all.” Similarities across the species were a strong argument for evolution, but in fact biology is full of unique designs, particular to one or a few species.

Such one-off, “lineage specific” designs are “bizarre” for evolutionists. So while there are design reasons for the ostriches four kneecaps, on the ordinary view of the evolution of each being, we can only say that so it is.