A meat-eating dinosaur that terrorized its plant-eating neighbours in South America was a lot deadlier than previously thought, a University of Alberta researcher has found.
Scott Persons said the 23-foot-long Carnotaurus had a huge tail muscle, which the researcher believes made it one of the fastest-running hunters of its time. This dinosaur was a true speed demon, he said.
A close examination of fossil tail bones of Carnotaurus showed its caudofemoralis tail muscle had a tendon attached to its upper leg bones that pulled the legs backward powerfully to give the carnivore more power and speed in every step, a university release reported Friday.
Person's research suggests the tail of the Carnotaurus was the heaviest and thickest one out there, relative to its body size.
On the Carnotaurus, it's absolutely massive, Persons said. He began his research by dissecting the tails of modern-day lizards and crocodiles, measuring them and studying their vertebrae to see where the tail muscles -- the caudofemoralis muscles -- attached to their upper leg bones via tendons.
When this tail muscle contracts, what it does is pull the leg backwards, and when a crocodile or lizard is walking or running, all of its locomotive power, all of its forward thrust, comes from the contraction of that muscle pulling the leg backwards, said Persons, describing the anatomy of the movement.
He estimated the tail of the Carnotaurus was about three meters long and, where it attaches to the dinosaur's body, about as thick as a large watermelon. More telling is that Persons estimated the tail to weigh about 223 kilograms, about 15 percent of the beast's body weight.
No one ever had a good idea about how big this muscle was, Persons said.
Persons published these findings in PLoS ONE on Friday, with supervisor Philip Currie, a paleontology professor at the University of Alberta.