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Strange Headgear Led to Big Dinosaurs

Theropod dinosaur skulls showing unornamented (Acrocanthosaurus NCMS 14345, left) and ornamented (Cryolophosaurus FMNH PR 1821, right) styles.

Theropod dinosaur skulls showing unornamented (Acrocanthosaurus NCMS 14345, left) and ornamented (Cryolophosaurus FMNH PR 1821, right) styles.

Tyrannosaurus rex and other large meat-eating theropods were the biggest baddies on the prehistoric block, and ornaments on their heads could help us figure out why. New research from NC State shows that theropod dinosaur species with bony crests, horns and knobs evolved to giant body sizes 20 times faster than those species lacking such embellishments.

Additionally, the research shows that theropod dinosaurs most closely related to birds abandoned the hard-ornaments strategy of their ancestors and likely used feathers for visual communication.

Using observational data and computer modeling, the researchers found that for theropods weighing under about 80 pounds, bony cranial ornamentation did not evolve. Above that threshold, 20 of the 22 largest theropods had ornamentation. And it turns out that once a theropod species developed some style of head display, subsequent species would take large leaps toward gigantic body sizes every 4 to 6 million years. Large theropod lineages containing species without ornamentation—such as Acrocanthosaurus—did not achieve giantism as rapidly as their ornamented brethren.

“We were surprised to find such a strong relationship between ornaments and huge body size in theropods,” says biological scientist Terry Gates. “Something about their world clearly favored bling and big bods.”

This article was originally published by NC State News.