Raptors’ short legs made them slow runners, new study says

A new study from the University of Alberta shows a dinosaur’s speed is all in its legs.

Scientists looked at carnivorous dinosaurs who had to hunt down their prey, and found those with longer lower legs were capable of running faster than those with shorter lower legs.

The spacing of the rare footprints — each measuring about 18 inches in length — suggests a gait of 4.5 to 8 kilometers per hour (2.8 to 5 miles per hour), according to a paper describing the research. That is slower than the average human, who can run about 11 miles per hour over short distances.

But “the tyrannosaur that made the footprints was just walking, and it was walking over muddy, mucky ground,” said the scientist, Scott Persons, a graduate student in paleontology at the University of Alberta. “And it was clearly a walk and not a run because of how the feet were positioned” — offset, indicating a sort of “bowlegged” gait.

The series of three footprints in sandstone dating back 66 million years are believed to have been made by a young T. rex (or possibly a smaller tyrannosaur known as Nanotyrannus lancensis). The stride length and hip height were plugged into a standard equation to arrive at the estimate of the dinosaur’s gait speed.

The finding “discounts previous speculation that tyrannosaur walking speeds were notably slower than those of other large theropods,” Persons and his co-authors wrote in the paper, which was published in the June 2016 issue of the journal Cretaceous Research. But it says little about tyrannosaurs’ maximum speed.

Agencies/Canadajournal