Domed Dinosaur Was King of the Head Butt

Researchers surveyed the heads of a large number of modern animals as well as one of the world's best dinosaur fossils, the Stegoceras specimen from the University of Alberta. They found that the bony anatomy of some pachycephalosaur domes are better at protecting the brain than in any modern head butter. The results of their research is published in PLoS ONE.

"Pachycephalosaur domes are weird structures not exactly like anything in modern animals. We wanted to test the controversial idea that the domes were good for head butting," says co-author Dr. Eric Snively, University of Calgary alumnus and post-doctoral researcher in biomedical engineering at Ohio University.

"Finding out brings us closer to their social lives: were pachycephalosaurs more likely just showing off their domes like peacocks with their tails, or were they also cracking their heads together like musk oxen?"

Using CT scanning and a new statistical method for diagnosing behavior in fossil animals, the researchers compared the bony-headed dinosaur with 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. "We looked at the actual tissue types in the skulls and heads of the animals."

Head butting is a form of male-to-male competition for access to females, says Dr. Jessica Theodor, co-author and associate professor in the biological sciences department at the University of Calgary. "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."

Most head-butting animals 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. Stegoceras was a small pachycephalosaur about the size of a German shepherd, and lived about 72 million years ago.

Llamas would crack their skulls head butting and giraffes aren't very good at it. "They swing their necks at each other and try to hit each other in the neck or the side," says Snively. If giraffes do manage to butt heads, they can knock each other out because "Their anatomy isn't built to absorb the collision as well as something like muskox or big horn sheep."
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Rare Insect Fossil Reveals 100 Million Years of Evolutionary Stasis

Researchers have discovered the 100 million-year-old ancestor of a group of large, carnivorous, cricket-like insects that still live today in southern Asia, northern Indochina and Africa. The new find, in a limestone fossil bed in northeastern Brazil, corrects the mistaken classification of another fossil of this type and reveals that the genus has undergone very little evolutionary change since the Early Cretaceous Period, a time of dinosaurs just before the breakup of the supercontinent Gondwana.

The findings are described in a paper in the open access journal ZooKeys.

"Schizodactylidae, or splay-footed crickets, are an unusual group of large, fearsome-looking predatory insects related to the true crickets, katydids and grasshoppers, in the order Orthoptera," said University of Illinois entomologist and lead author Sam Heads, of the Illinois Natural History Survey. "They get their common name from the large, paddle-like projections on their feet, which help support their large bodies as they move around their sandy habitats, hunting down prey."

Although the fossil is distinct from today's splay-footed crickets, its general features differ very little, Heads said, revealing that the genus has been in a period of "evolutionary stasis" for at least the last 100 million years.

Other studies have determined that the region where the fossil was found was most likely an arid or semi-arid monsoonal environment during the Early Cretaceous Period, Heads said, "suggesting that the habitat preferences of Schizodactylus have changed little in over 100 million years."
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