Back in the Cretaceous period, 145 to 66 million years ago, dinosaurs dominated the land and sky. They also, a new paper argues, terrorized the aquatic realm. Recent fossil evidence has revealed that Spinosaurus aegyptiacus, among the largest of all known carnivorous dinosaurs, was a creature of the water, with a center of gravity and a giant tail fin perfect for swimming. The same paper shares robotic modeling by two Harvard scientists that shows how that large, flexible tail fin — unique among dinosaurs — would have given the giant predator a deadly propulsive thrust in the water, similar to a salamander or crocodile tail.
The paper, “Tail-Propelled Aquatic Propulsion in a Theropod Dinosaur,” in the April 29 issue of Nature, uses new fossil evidence and robotically controlled models created by Harvard co-authors Stephanie E. Pierce and George V. Lauder, professors of organismic and evolutionary biology, to show its power.
Pierce said the new fossils were necessary to make their argument, as much of the fossil evidence of Spinosaurus, unearthed by German paleontologist Ernst Stromer, had been destroyed in World War II. University of Detroit paleontologist Nizar Ibrahim, the Nature paper’s lead author, had located more traces of the dinosaur in Morocco in 2014, and in 2018 he went back, successfully excavating extensive Spinosaurus remains. The fossils included tail vertebrae with meter-long spines that seemed to form an expanded paddle, raising questions as to what the tail was used for.