All-species fitness

OK, a funny.

Image: The Awkward Yeti

Tyrannosaurus rex was a huge meat-eating dinosaur, with thick, heavy skull and a 4-foot-long (1.2-meter-long) jaw, designed to crush bones.

Scientists think T. rex could eat up to 500 pounds (230 kg) of meat in one bite.

T. rex was not just huge and immensely powerful: s/he could outrun all but the fastest of today's marathoners. Results of several studies suggest that this ferocious predator could run 10 to 25 mph (17 to 40 km/h) in order to catch its dinner.

Catch being the key word here -- its tiny arms were unlikely to seize another animal, and they were too short to reach its mouth.

So T. rex had to catch prey — mainly herbivorous dinosaurs, but could include smaller tyrannosaurs — in its monster jaws. And apparently, it wasn't above scavenging when a carcass was available.

Coincidence?  The largest and most complete T. rex skeleton found to date was nicknamed Sue (after its discoverer, paleontologist Sue Hendrickson).

Sue and her fellow predators had arms about as long as a large human's but had 12 m (40 ft) high, 5,400 kg (11,900 lb) bodies, so the funnies are not exaggerating.

So what did this monster do with its really short forearms?

Scientists think T. rex could use the small but super strong arms to hold a struggling prey animal while killing the animal with what are thought to be the most powerful jaws of any terrestrial animal ever.

The arms might also have helped this giant killer get up from lying down after a nap.

They just weren't good for clapping.