this tyrannosaur rex still on the throne as the greatest predator of all time. About 12 meters long and almost six meters tall, it can exert up to six tons of pressure with one bite of its powerful jaw, made up of 60 sharp teeth. can split a car in two. However, for one of the scariest monsters to ever exist on Earth, it has been teased in endless memes. Mainly because of a curious body trait: short and useless arms.

Why were they so small? Science has produced various theories.

Scientists have been trying to unravel this mystery since archaeologist Barnum Brown unearthed the first complete T. rex skeleton in 1904. And of course, the puzzle is even more complicated. this creature is 68 million years old. Still, it hasn’t deterred scientists from pursuing its evolutionary benefits. Hypotheses range from grabbing the female during sex to not biting themselves to a solution. What is clear is that their ancestors had larger arms, so there was a clear selective evolution causing their limbs to shrink.

Some paleontologists even suggest that the arms have no function. They were too short, could not touch each other or reach their mouths, and their range of motion was so limited that they could not reach far, neither forward nor upward.

Now, new research from UC Berkeley led by paleontologist Kevin Padian and published in the journal Acta Palaeontologica Polonica shows that Tyrannosaurus rex’s arms got shorter over time. to prevent accidental or deliberate amputationI. That way, when a herd of T. rex rallied on a carcass for feeding with their massive heads and powerful jaws, they wouldn’t rip off their own limbs in the process.

Imagine prey of this size and several adult T. rex ripping and shredding the victim’s flesh. Having loose limbs would not be advantageous may also be subject to interruptions. Padian hypothesizes that natural selection favored shorter forelimbs, as weapons have little use for carnivores. However, his arms were known to be quite strong: analysis has shown that a T. rex arm can lift up to 400 pounds, even though it’s pretty useless with coordination.

Henry Fairfield Osborn, who described and named T. rex, could be “breast braces”, the limbs that hold the female in place during mating. Something similar to the pelvic clips of some sharks and rays that have modified fins. But there is no evidence of that. Also, females have the same limbs and the arms are very close to the body, so it is not clear how effective they will be in holding or surrounding such a large animal.

Other scientists theorized that the arms were used as a lever to get the T. rex off the ground in case of a fall. Like a cane. Or maybe they just slept like that. There must be a way to get back up. Other paleontologists believe the arms were used to grasp writhing prey before they were dispatched. Steven Stanley of the University of Hawaii at Manoa noted that they are claw-like, capable of slashing and killing prey, and inflict mortal wounds on prey.

However, the hypothesis that received the most weight in addition to avoiding accidental amputation was that of allometric growth. well disordered evolution of organs We see the irregular rhythm of an animal’s body in humans and most vertebrates. For example, babies’ limbs often grow larger than their heads, which are already quite large at birth.

Finally, some claim they are vestigial: an evolutionary relic. Arms like the wings of today’s flightless birds such as ostriches and emus were no longer needed. As discussed in this National Geographic article, evolution sometimes works by subtraction. Stripping things, not adding. Older organisms had more segments, so there is a constant loss of elements. That is, if an organism survives in its environment because it is simple, it will endure. However, none of these theories and speculations seem to have been fully proven.