Dinosaurs Inside and Out

Growing Bones

What can paleontologists tell about the lifestyle of a large carnivore (theropod) from its fossil bones?

The Tyrannosaurus is currently the most recognizable of the large carnivorous dinosaurs. Its skeleton had heavy, large bones, with massive vertebrae, hip girdle, and thigh bones. The upper foot bones (metatarsals) were locked together for strength, while the toes were powerful and short. The knees show evidence of thick cartilage, similar to modern birds.

There are two scenarios concerning the speed and mobility of the Tyrannosaurus based on the animal’s skeletal structure, and both sides point to the same evidence to bolster their claims. One group thinks that the skeletal structure of a Tyrannosaurus caused the animal to move at a slow pace, which limited its main hunting abilities to either scavenging or ambush techniques. The other group suggests that the dinosaur’s bone structure, along with the animal’s massive musculature, enabled the Tyrannosaurus to run and sprint, making it an active, dangerous hunter.

Until more direct evidence is gathered, the most agreed upon theory is based on a major deduction: the Tyrannosaurus would need more meat than was available from scavenging, so it would have to hunt. To do so, it would have to at least match the speed of its prey. In other words, it would have to keep up with such dinosaur prey as the herbivores Triceratops and Edmontosaurus (ornithischians), both of which are thought to have reached 9 to 12 miles (14 to 19 kilometers) per hour for short bursts.


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