University College London – Researchers analyzed data from 82 theropod species and found a strong correlation between shrinking forelimbs and the evolution of larger, more powerful skulls and jaws. (Representational image: Gorgeous) Scientists have long been fascinated by the short arms of Tyrannosaurus rex. However, T.

rex was not the only carnivorous dinosaur with reduced forelimbs. At least five groups of two-legged theropod dinosaurs independently evolved short arms over time, according to a new study led by Charlie Roger Shire of University College London.

“It’s a case of ‘use it or lose it,’” Scherer said in a statement. Researchers analyzed data from 82 theropod species and found a strong correlation between shrinking forelimbs and the evolution of larger, more powerful skulls and jaws. The study, published in Proceedings of the Royal Society B: Biological Sciences, shows that many theropods relied on their heads and bite force rather than their arms to hunt down prey.