Several years ago, the paleontological world heralded the discovery of a fossil called Tiktaalik roseae. Some scientists claimed it as a perfect missing link between fish and amphibians, and so it started appearing in school and university textbooks. However, the discovery of a series of footprints in Poland, made by a four-legged animal, has changed everything. That's because these foot prints were dated according to the same evolutionary ideas at 18 million years older than Tiktaalik. Therefore, from an evolutionary perspective, if four-legged animals existed before Tiktaalik, then Tiktaalik cannot be the transition between fish and four-legged land animals that it was claimed to be.
Indeed, these footprints are so significant that they have prompted some scientists to say: "we thought we'd pinned down the origin of limbed tetrapods. We have to rethink the whole thing."
Isn't it amazing how just a little bit of new evidence can completely undermine a neat evolutionary story?