With its massive, chomping jaw and fierce expression, Tyrannosaurus rex may be the most fearsome dinosaur of all. Scientists generally assumed that with their long legs, T. rexes could run at top speed to catch prey. But some researchers now think that the dinosaur’s long legs were more for endurance and efficiency than for running.
The researchers calculated how much energy dinosaurs of different weights and leg length would need to move around, and they argue that for heavy dinosaurs like T. rex, long legs saved energy while they searched for prey but didn’t necessarily help them sprint.
Hunters like T. rex spend much of their time roaming in search of food, and the researchers believe that efficiency was more important than speed for the biggest theropods like T. rex. But theropods include a wide range of meat-eating dinosaurs who generally walked on two legs. Some were as small as half a pound, as light as a rat, while others weighed nine tons, heavier than the biggest elephant. Fortunately for the lighter theropods, who were hunted as well as hunters, their long limbs did let them run at top speeds.
- News release from the University of Maryland: T. rex’s long legs were made for marathon walking
- News release from the journal PLOS ONE: T. rex was a champion walker, super efficient at lower speeds
- Research article: The fast and the frugal; different strategies drove long limbs in theropod dinosaurs