T. Rex's Tiny Arms Were Actually Deadly Weapons

Wednesday, 08 November 2017 - 11:18AM
Wednesday, 08 November 2017 - 11:18AM
T. Rex's Tiny Arms Were Actually Deadly Weapons
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Image credit: YouTube
If you ever wondered if Tyrannosaurus rex's massive jaws were compensating for its tiny arms—you're dead wrong. T. rex's arms were far from the useless appendages we've long depicted them as; in fact, they were actually dangerous slashing weapons, according to a paleontologist's new report.

Choose any pop culture depiction ever of the Tyrannosaurus rex, from Jurassic Park to Toy Story, and you'll find references to its awkward proportions, specifically its massive head and its short stubby arms.

There is no question that the apex predator's size and its jaws were the keys to its dominance, but a paleontologist at the University of Hawaii now argues that those diminutive forelimbs were more lethal than people think.

In a recent presentation at the Geological Society of America, Steven Stanley argued that our thinking of T. rex arms as small is inaccurate. While they were small compared to the rest of the animal, each limb was around three feet long. Stanley also said that the bones in the predator's arms were a great help.

"A large coracoid indicates that the arms were very strong," he wrote, "not only slightly longer than the leg of a six-foot man but also of similar girth...The arm bones were quite robust and would readily have sustained the impact of slashing."

Add to the strong, three-foot-long arms a set of three-inch-long claws and ball-and-socket-like shoulder joints, and Stanley says that the T. rex would have been a nightmare for smaller dinosaurs.

"Its short, strong forelimbs and large claws would have permitted T. rex, whether mounted on a victim's back or grasping it with its jaws, to inflict four gashes a meter or more long and several centimeters deep within a few seconds—and it could have repeated this multiple times in rapid succession."

Stanley's arguments were not enough to sell everyone on the idea that Tyrannosaurus rex's arms were much of a threat.

"I would expect it could cause some decent damage if it struck," paleontologist Thomas Holtz told National Geographic, "but in order to deploy [the arm], Tyrannosaurus would basically have to push its chest up against the side of the victim...In such a position the tyrannosaur wouldn't be able to use its far more powerful armament: its massively powerful jaws."

Whether they were useless vestigial limbs or powerful slashing devices, it would not matter much if you were close enough to a living T. rex to measure its claws, but it's always easier to make jokes about the bully behind his back.
Science News
T. Rex's Tiny Arms Were Actually Deadly Weapons