You have evolution to thank for every bizarre-looking bird in existence. Sexual selection is a powerful tool for breeding the brightest, fluffiest feathers—if the lady birds like ‘em, males will keep ‘em.
It’s easy to forget that non-sexual selection can create stranger adaptations—ridiculous appendages and odd proportions that we giggle at—that are in fact no less useful than pretty plumage. It’s possible that even T. rex arms served some purpose. A recent presentation at the annual Geological Society of America meeting suggested that their stumpy yet powerful arms may have been useful slashing tools, though paleontologists aren’t entirely convinced. Jaws seem far more useful, especially given the short range T. rex would have had with its front claws. Useful or not, the giant dinos did alright for themselves, barring that whole meteorite thing. But longer arms wouldn’t have helped them prevent worldwide destruction.
