Fossil hunters can predict where to dig based on evolutionary theory, and it works

Shubin recounts how his team didn't stumble on the fish-to-land-animal transitional fossil Tiktaalik by accident — they deliberately searched rock layers of a specific geological age, roughly 375 million years old, in locations that would have been ancient river deltas, because evolutionary theory predicted that's exactly where and when a transitional creature between fish and four-limbed land animals should appear in the fossil record.

After years of expeditions to the Canadian Arctic, they found it: a fish with a flattened head, eyes on top like a crocodile, and, crucially, wrist-like bones inside its fin capable of bearing weight, showing a body plan literally caught between swimming and walking.

Shubin uses this story as a demonstration of evolutionary theory's predictive power, not just its explanatory power after the fact — the fact that scientists could specify in advance what rock layer, what appearance, and roughly what anatomy such a fossil should have, and then actually find it, is treated as one of the strongest confirmations of the theory's validity.

Takeaway: evolutionary theory isn't just a retrospective story — it successfully predicted where to dig for a fish that could almost walk.