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Duck-Billed Dinosaurs "Outgrew" Their Predators

from National Geographic News

Talk about being a big baby. The duck-billed dinosaur Hypacrosaurus grew three to five times faster than the fearsome predators that hunted it, reaching its full size by age ten, according to a new study.

Unlike other plant-eating dinosaurs, duckbills such as Hypacrosaurus didn't have piercing horns, dagger-like teeth, or hulking body armor. So the ability to grow bigger faster provided the animals with a size advantage that likely served them well in their early years.

For example, baby duckbills were probably about the same size as Tyrannosaurus rex hatchlings, said study co-author Drew Lee of Ohio University's College of Osteopathic Medicine. But by five years old the duckbill would be the size of a grown cow, while the T. rex would be only as big as a large dog.