If it was convergent evolution, I think we'd expect the actual amino acid sequences of the proteins to differ just as much at the functional points as at the purely structural points, instead of showing more sequence similiarity like they do.
(Convergent evolution is where 2 unrelated species evolve a superficially similar solution to the same engineering problem, isn't it? In that case, the similarities should break down upon closer analysis, such as in the amino acid or the DNA sequences.)
Well done. Although it applies to the molecular as well as species, so it cab be also similar seeming mechanisms.
Can you give examples of a species (or organismal) covergent evolution and for extra credit a protein example?