Poor T. rex. We all like to make fun of its “puny” arms.
Yes, T. rex arms were about 3.3 ft (1 m) long, and compared to the rest of its (up to) 40 ft (12.2 m) long body, the arms were short. But, they were far from useless.
A study published in 2001 by Kenneth Carpenter and Matt Smith found that T. rex arms were still “stoutly built and well muscled.” After looking at the structure of the arms and taking into account the thick bones and large areas where muscles attached, they found that T. rex biceps were 3.5 times as powerful as ours. This works out to easily curling about 145 lb (66 kg) with a single arm.
Relatively speaking, since the rest of T. rex was so large, and its bite force so much stronger, that’s not a great ratio. However, T. rex may have used its arms, with its large, sharp claws, to hold struggling prey.
Check out our podcast, episode 200, to learn even more about T. rex and its (not) puny arms.