Duck-billed dinosaurs grew to survive

ATHENS, Ohio, Aug. 6 (UPI) -- U.S. scientists say they've determined the duck-billed dinosaur, or hadrosaur, grew much faster than its predators, providing a defense of size superiority.

The researchers said the hadrosaurs, with long limbs and soft bodies, had few defenses against predators such as tyrannosaurs. But new research on the bones of the plant-eating hadrosaur Hypacrosaurus suggests its rapid growth provided a defense.

The research determined it took 10 to 12 years for Hypacrosaurus, which lived 67 million to 80 million years ago, to become fully grown. Tyrannosaurs, however, reached adulthood after 20 to 30 years, said Drew Lee, a postdoctoral fellow at Ohio University who co-authored the study with Lisa Noelle Cooper, a doctoral student at Kent State University.

"Our duck-billed dinosaur grew three to five times faster than any potential predators that lived alongside it," Lee said. "By the time the duck-billed dinosaur was fully grown, the tyrannosaurs were only half grown -- it was a huge size difference."

The research appears online in the Proceedings of the Royal Society of London: Biological Sciences.