Top Story: June 30, 2011

Best Head-Butter of All Time!

DomedDino

That’s right, today’s Science Today is almost like a WWE match as we ponder the question, which species, living or otherwise, is the best head-butter of all time?

In this corner, weighing in at 2,600 pounds, a 17-foot tall mammal, the giraffe.

And in this corner, weighing in at about 60 pounds, a 6½-foot pachycephalosaur, Stegoceras validum.

And judging this fierce competition, researchers from the University of Alberta.

Bell rings. Head-butting ensues… Well, virtually, anyway.

And the winner, published this week in PLoS ONE: the Stegoceras.

The small dinosaur with the domed head may have only been the size of a German Shepherd, but it was basically built for head-butting, the scientists discovered.

Actually, giraffes are terrible at head-butting. “They swing their necks at each other and try to hit each other in the neck or the side,” says study co-author Eric Snively, PhD. If giraffes do manage to butt heads, they can knock each other out because "their anatomy isn't built to absorb the collision.”

Using CT scanning and a new statistical method for diagnosing behavior in fossil animals, the researchers compared the bony-headed dinosaur with many other modern ungulates (hoofed animals) that engage in different kinds of combat.

“Our analyses are the closest we can get to observing their behavior. In a way, we can get ‘inside their heads’ by colliding them together virtually. We combined anatomical and engineering analyses of all these animals for a pretty thorough approach,” says Snively. Sounds like fun.

Most current head-butting animals, like big horn sheep and musk ox, have domes like a good motorcycle helmet. “They have a stiff rind on the outside with a sort of a spongy energy absorbing material just beneath it and then a stiff, really dense coat over the brain,” says Snively.

The Stegoceras had an extra layer of dense bone in the middle. According to co-author Jessica Theodor, PhD, "It's pretty clear that although the bones are arranged differently in the Stegoceras, it could easily withstand the kinds of forces that have been measured for the living animals that engage in head butting.” Making it a better head-butter than the best living head-butters!

And why all the head-butting? It’s is form of male-to-male competition for access to females, says Theodor. Or, as Wired UK put it:

Ladies love a good head-butter.

Nice work, Stegoceras.

Image: Eric Snively, Jessica M. Theodor,  PLoS ONE 2011

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