Tyrannosaurus rex's small arms were vestigial and functionally useless for any significant task.
T. rex arms, while short relative to leg length, were powerful and muscular with bone and muscle attachment sites indicating functional utility. Biomechanical studies show T. rex could bench-press approximately 400 kilograms. Arms were likely used for grasping prey, restraining struggling meals, and assisting in rearing up or rising from a prone position. The arms maintained forearm pronation-supination capacity enabling gripping functions. Short arms reflected specialisation for a powerful bite and stable stance rather than functional uselessness.