T. Rex's Tiny Arms Were the Price of Evolving a Lethal Skull

For over a century, the tiny arms of Tyrannosaurus rex stood as one of paleontology's most enduring puzzles — a seeming contradiction in a creature otherwise built for dominance. New research published in Proceedings of the Royal Society B now offers an answer rooted not in failure, but in the quiet logic of evolutionary trade-offs: the T. rex's skull became so devastatingly powerful that strong arms were simply no longer part of the bargain. In the long arithmetic of natural selection, what looks like a deficiency often turns out to be the signature of a deeper optimization.