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When you cannot prove evolution occurred simply claim it did but the fossil record does not exist. It's the old dog-ate-my-homework trick.

When looking at an organ as complex as the eye, we are struck by the incredible complexity of a trait that requires so many intricate parts, all of which must work together. How could such a complex trait ever evolve in the first place? Darwin raised this issue in On the Origin of Species:
But Darwin was certain that natural selection could and did surmount this difficulty by small successive changes, each of which provided a benefit compared to the last version of the eye. The very next sentence of Darwin’s quote reads,
Evolutionary biologists L. V. Salvini-Plawen and Ernst Mayr have expanded on Darwin’s hypothesis, laying out a series of intermediate forms that could represent one plausible sequence by which the eye evolved in gradual steps (Salvini-Plawen and Mayr 1977). Because eyes are made of soft tissue that does not fossilize well, Salvini-Plawen and Mayr used currently living species to show examples of the sorts of eye morphologies that may have been present in ancestral forms, and they found that indeed current forms can be arranged into a series of steps, each only slightly more complex than the previous, that would lead from a simple lightsensing pigment spot to a focusing eye with a lens. The aim was not to reconstruct the exact sequence by which eye evolution did occur—in fact, there is no single answer to this question, given that the lensed eye evolved in parallel in several different lineages. Rather, this work was meant to illustrate that the focusing eye, elaborate as it may seem, could have evolved in gradual steps, each of which was fully functional and each of which improved on the visual acuity of its predecessor.

But is this feasible? Is there enough time for this to have happened? Dan-Erik Nilsson and Susanne Pelger used computer simulations to explore how long it might take to evolve a focusing eye from a simple light-sensitive patch (Nilsson and Pelger 1994). They assumed that individual mutations had only small phenotypic effects, and they made conservative assumptions about the rate at which natural selection would proceed under these circumstances. They found that the focusing eye could have evolved in fewer than half a million years—a very short time compared to the 550 million years since the first simple eyes occurred in the fossil record. Darwin’s intuitions were correct. Complex focusing eyes have evolved by natural selection, and they have done so independently along several lineages on the tree of life. Each of these lineages may have proceeded along a different path; but along each path, every small step could have been functional in itself, and could have improved on the visual system that preceded it.