University of Utah paleontologists David Peterman and Kathleen Ritterbush know that it's one thing to use math and physics to understand how ancient marine creatures moved through the water. It's another thing to actually put replicas of those creatures into the water and see for themselves. They're among the scientists who are, through a range of methods including digital models and 3D printed replicas, "de-fossilizing" animals of the past to learn how they lived.