Tyrannosaurus rex is perhaps the most famous dinosaur and maybe even the most famous fossil animal. It has long been a source of curiosity as to why is has such small arms though. What could the possible function be? This week we take a look at a new paper has taken a quantitative approach to this age long-thorny problem to investigate the evolutionary changes that might have led to such unusual anatomy. Indeed it happened not just one, but five times in the theropods. Let's find out why and how!

This week's paper is "Drivers and mechanisms of convergent forelimb reduction in non-avian theropod dinosaurs" by Charlie Scherer and colleagues published in Proceedings of the Royal Society in May 2026. https://doi.org/10.1098/rspb.2026.0528

Wide screen art by Arvalis/Saurian.