Paleontologists rarely find complete skeletons, so they're often faced with the task of creating realistic substitutes for the missing bones. Incomplete skeletons are even more common with fossil mastodons because humans sometimes butchered the massive, elephant-like animals and hauled off whole hunks of meat, often with the bones, says U-M mastodon authority Daniel Fisher, a professor with joint appointments in the Museum of Paleontology and the departments of Geological Sciences and Ecology & Evolutionary Biology.This is a great idea, and it's wonderful that UMich can get the technology. Borrowing bones is obviously a bad idea, and this technique allows precise matching of parts using well-documented scaling rules.
In the past, scientists and exhibit preparators used a variety of techniques—borrowing bones from another specimen of the same species, size and stage of development, for instance, or manually sculpting a replacement bone, based on measurements and comparisons with the rest of the skeleton.
Now, however, Fisher and his team are using 3-D digitization, modeling and rapid prototyping—technologies that are widely used in manufacturing, especially in the automobile industry—to produce full-scale replicas of the bones they lack.
It's worth noting that this means producing missing parts, not making things up wholesale.