You are what you eat, even if you are a dinosaur.
University of Alberta scientists learn more about the lives of the ancient lizards by examining their teeth to see how they used them – and what else. 19659002] "If we want to fully understand how these animals live, we need to understand what they eat and how they eat," said Ryan Wilkinson, a student and co-author of a paper published in Current Biology .
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Wilkinson and his colleagues investigated scratches left by battling prey on the teeth of three different birds of prey and read them up like grooves a record to see how the dinosaurs tore into lunch. They then used techniques that were developed to test the strength of bridges to suggest which prey was preferred.
"The phrase we use in the work is 'stitch and pull'," Wilkinson said.
The scientists looked at three similar dinosaurs ̵
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Everyone was eating meat, stood on their hind legs, was about two meters long and weighed between 15 and 25 kg. They lived in the same environment around the same time and are often found together in fossil beds. All three had notches like steak knives on the back of the teeth to cut through meat.
The team first examined grooves on the teeth.
The scratches ran in two directions: up and down and sideways. "That's proof that dinosaurs ate by beating their prey and then ripping the meat off the carcasses," Wilkinson said.
"There's a vertical puncture, then an oblique cut when the animal closes its mouth while pulling its head back."
This is how all carnivorous dinosaurs could have eaten. Teeth of Gorgosaurus, a gigantic nine meter cousin of T. rex, show the same pattern.
But the teeth had more to say. Troodon's teeth, called denticles, were much larger than those of the others.
"They have those big hook-shaped teeth, really bizarre," Wilkinson said.
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The team attempted to understand what these ticks reveal about Troodon's diet, and built a computer model of their teeth and subjected them to stress tests
"We use this technique to test the stresses exerted on the teeth when brushing teeth. We applied forces at different bite angles. "
When the bite with the most common angle of the scratches appeared, the teeth worked well. As the angle drifted away from the scratches, the models indicated that Troodons teeth began to break.
"Fighting prey can really exert an uncontrollable force on the teeth at angles that are not really ideal," Wilkinson said  If the prey that recoils is likely to break its teeth, you'll probably chase something else , Teeth suggest that Troodon went for smaller, slower prey animals – even carrion – and left the more industrious meals to Dromaeosaurus and Saurornitholestes
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The study explains how different dinosaurs populated different niches in their old ecosystems. It's one of the first times that such techniques have been applied to meat-eating dinosaurs, Wilkinson said.
"There is much more room to look more closely at it."