What can Tyrannosaurus Rex's short front paws do?

What can Tyrannosaurus Rex's short front paws do?

As one of the most famous dinosaurs known, and perhaps the strongest carnivore in the world, there is a part of Tyrannosaurus Rex that we will never understand-those front paws that look like a joke. On these huge bodies, which are about 13 meters long, about 5 meters high at the shoulder, full of teeth and weighing about 9 tons on average, such mini forelimbs look almost like an ornament. So most people think it is a vestige of limb degeneration, similar to the blind eye of cave fish.

In fact, even many paleontologists believe that these forelimbs are as useless as twigs used to replace arms when children make snowmen. Only Tyrannosaurus rex knows what they can do.

According to a recent report in The Economist, Sarah Birch, a researcher from the State University of New York at Stony Brook, recently presented her research results at the annual meeting of the American Society of Vertebrate Paleontology. She has been trying to solve the mystery of Tyrannosaurus Rex's forelimbs. Although she can't prove their function, Birch thinks these forelimbs are really useful, not the product of degeneration.

What made Birch come to this conclusion was the muscles of Tyrannosaurus Rex and its ancestors-precisely, the attachment points and muscle groups of the forelimb muscles. If these forelimbs really degenerate gradually under natural selection, then this change will be faithfully reflected in fossils of different periods.

Birch studied the arrangement of muscle attachment points between Tyrannosaurus Rex and its 10 close relatives, and deduced the muscle movement pattern. Comparing this information with the "family tree" of Tyrannosaurus Rex, we can see whether there is a trend of degradation.

The result: there is no sign of muscle degeneration at all. The difference of individual muscle size is random, and there is no decreasing trend as a whole. However, in this "family tree", about 7 million years ago, the muscles changed considerably-that happened to be the time when Tyrannosaurus Rex appeared.

The changed muscles reduce the ability of forelimbs to retract into the body, but increase the ability to extend forward. Birch is not sure what this change means. It may be to catch prey, or it may be to communicate among dinosaurs with "dinosaur sign language", as people have recently proposed. Perhaps, it can help them pose after their huge bodies fall to the ground.

Only one thing is certain-no matter how you look at it, those thin little paws are still ridiculous.