The Atheist Perspective

Such evolutionary developments require millions of years. Modern science has only existed for a few hundred. The question is thus absurd. It's like asking us to repeat the production of the Grand Canyon to confirm it resulted from river-basin erosion over the course of ten million years. We don't have to do that. The evidence is already conclusive that that's how the Grand Canyon formed. So, too, the development of phyla, classes, and orders. The evidence for the evolution of all phyla from a common ancestor is far stronger than the evidence even for the Big Bang, which we also didn't observe directly, but conclusively infer from abundant surviving evidence.

Transitional Forms and the Evolution of Phyla