Speculation and theory play useful roles in the scientific process. When evidence is unavailable or incomplete, theories and models let us test out ideas that we can’t yet prove.
Evidence is often incomplete where fossils are concerned. Old bones get chewed by predators, scattered, dissolved, buried, broken, and bent. The few fossils that survive to be discovered are rarely intact, leaving scientists to put together the pieces, such as they are, and wonder about the rest.
Thanks to a modern fusion of virtual reality and 3-D printing technologies, scientists can undo some of the ravages of time. Bone fragments can be scanned into a computer, then digitally reassembled in any number of plausible ways.
A skull squashed by the pressure of overlying rock can be virtually unsquashed. The missing half of a face can be summoned to mirror the existing half. The final result—or more often, the collection of possible results—can then be printed in three dimensions to yield replicas of those long gone.